REPORT

OP THE

STATE BOARD OF AGRICULTURE

ON THE WORK OF

EXTERMINATION OF THE GYPSY MOTH.

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JANUARY, 1898.

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BOSTON :

& POTTER PRINTING CO., STATE PRINTERS,
18 POST OFFICE SQUARE.
1898.

REPORT

OP THE

STATE BOARD OF AGRICULTURE

ON THE WORK OP

EXTERMINATION OF THE GYPSY MOTH,

JANUARY, 1898.

BOSTON :

WRIGHT & POTTER PRIXTIXG CO., STATE PRINTERS,
18 POST OFFICE SQUARE.

18-98.

TABLE OF CONTENTS.

PAGE

Brief description of the gypsy moth, . . 5

Habits of the caterpillars, . . ....... 5

Food plants, .... . . .6

Letter of transmittal, 7

Report of the committee, . ... ..... 9

Balance of appropriation on hand Jan. 1, 1897, 9

Prompt action of Legislature, . . ... 9

AVork in woodlands, . 10

Reduction of the force, 11

Results of the year's work, 11

Future work, .... 13

Endorsements of the work of the committee, ...... 14

Report of Prof. J. 13. Smith 15

Financial report, 15

Report of the entomologist, .... 17

Possibility of extermination, .... ..... 18

Amount necessary, 18

Economy of extermination, . 19

Report of the field director, 21

Winter and spring work, 21

Destruction of eggs in walls, 22

Burlapping, . . 23

Spraying, 23

Fall and winter work, 24

Summary of the year's work, 25

Details of work done, 26

False alarms, 26

Number of employees . .27

Condition of infested region, 28

Increase of the moth in woodlands, 43

Methods of work in woodlands, ... 44

Progress of extermination, 45

Need of large appropriations, .... ... .47

Conclusions, 49

Appendix 51

Arsenate of lead as an insecticide, 53

Arsenate of lead ; its manufacture and chemical composition, . . . 57

Experiments with insecticides, 70

Danger from the use of arsenate of lead, 90

Digestion in the larvre of the gypsy moth, 94

Notes on predaceous beetles, 102

The species of Podisus occurring in the United States, 112

PLATE I

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Drawn by Joseph Bndgham .

GYPSY MOTH

Geo.HWaJker &Co.,Boston

A.n Explanation of Plate I, with a Short Description of the
Different Forms of the Gypsy Moth and its Feeding
Habits.

THE EGGS.

[Fig. 8, cluster of eggs on hark ; Figs. 9 and 10, eggs magnified.]
The eggs are deposited in clusters, averaging about six hundred
eggs each, and covered with yellow hairs from the body of the female
moth. These egg-clusters are usually found in sheltered places on the
bark or in the crevices and cavities of trees, stumps and undergrowth ;
also on fences and buildings and in the crevices of stone walls and
other objects, near the plants or trees on which the insect feeds. The
eggs are laid in July, August and September, and hatch after the
foliage starts in the late spring or early summer of the ensuing year ;
therefore the insect passes the fall, winter and early spring in the egg.

THE LARVA OK CATERPILLAR.

[Figs. 6 and 7.]

When first hatched the caterpillars are less than one-fifth of an inch
in length. As they grow larger they may be seen in clusters upon the
trunks and branches of trees or in the cavities and other hiding-places
where they gather in June, July and the first part of August.

THE PUPA.

[Fig. 5.]

The. caterpillar when fully grown sheds its outer covering and be-
comes a pupa or chrysalis. This usually occurs in July or August.
The pupa may be found in the same situations as the eggs. In Massa-
chusetts the insect usually remains in the pupal state from ten to
thirteen days, emerging as a moth at the end of that period.

THE MOTH.

[Figs. 1 and 2, female; Figs. 3 and 4, male.]

The female moth usually deposits her eggs very near the abandoned
pupa case, and within a few hours after emerging from it. She dies
soon after. The male is a rapid flyer. The female does not fly.

HABITS OF THE CATERPILLARS.

The gypsy moth feeds only when in the larval or caterpillar state.
In Massachusetts the eggs of the g} T psy moth begin hatching about
April 20, and the young continue to emerge until the middle of June.
The length of larval life varies somewhat according to circumstances,
but probably averages at least ten weeks ; therefore the feeding season
in this country lasts about four months. When the caterpillars are first

6 EXPLANATION OF PLATE.

hatched from the eggs they are light in color and covered with whitish
hairs. In a few hours they assume a dark hue. They usually remain
on or near the egg-cluster until they change in color, and should the
weather be cold they sometimes remain for several days in a semi-
torpid condition upon the egg-cluster. If the temperature is favorable
they usually search for food before they are twenty-four hours old.
During the first few weeks of their existence they remain most of the
time on the leaves, feeding mainly on the under side. Their feeding
habits are so uncertain that no rule can be given which will apply to
all individuals, but before they are half-grown they generally begin to
manifest their gregarious instincts At that time and for the rest of
their existence as caterpillars they spend a large part of the day clus-
tered in sheltered situations, and feed principally at night, going up the
trees and out on the branches after dark and returning before daybreak.
When they are so abundant that the food supply is insufficient they
evince much restlessness, and feed in numbers during all hours of the
day and night. They may then be seen hastening to and fro, both up
and down the trees. Those which have fed sufficiently are at once
replaced by hungry new-comers, and the destruction of the foliage goes
on incessantly.

At such times the trunks and lower branches of trees are covered with a
moving mass of caterpillars, hurrying throngs are passing and repassing,
and nearly every leaf or denuded stem bears up one or more of the feed-
ino- insects. The rustling caused by their movements and the continual
dropping of excrement is plainly audible. On tall trees the larger
caterpillars appear to crawl to the higher limbs, and they seem to prefer
to feed well out toward the end of the branches. They do not feed gre-
gariously except when in great numbers ; therefore they seldom strip
one branch only, as do the larvse of the Euvanessa antiopa, but scatter
throughout the trees, eating a little from each leaf. Early in the
season when they are small and few in numbers, their ravages are
scarcely noticed ; but as they grow larger and more numerous, their in-
roads on the tree decrease the foliage area night by night, until suddenly
all the remaining leaves are eaten, and the tree is stripped in a single
night.

FOOD PLANTS.

The gypsy moth is known to destroy the foliage of nearly all native
and introduced trees and plants of economic importance. The list of
its food plants includes nearly all evergreen and deciduous trees, most
bushes, shrubs, vines and vegetables, and it has been seen to eat grass
and grain. Wherever the caterpillars become numerous they move
slowly, devouring nearly every green leaf and bud as they go. They
feed during a much longer season than the canker worm or the tent
caterpillar. In the months of June, July and August, 1891, trees which
had been stripped early in the season and whose leaves had again put
out were again defoliated by these caterpillars and kept bare all sum-
mer ; therefore, not only was all prospect of a fruit harvest destroyed,
but many trees were killed by this continual defoliation.

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To the Senate and House of Representatives of the Commonwealth of

Massachusetts.

I have the honor to present herewith to the General Court
the report to the State Board of Agriculture of the committee
of said Board having in charge the gypsy moth work. I
present also the reports of the director of field work and the
entomologist to said committee ; the three reports together
constituting the report of the State Board of Agriculture on
the extermination of the gypsy moth. The statement of
receipts and expenditures and the recommendations and sug-
gestions contained in said report, having been adopted by
said Board, are presented in accordance with the provisions
of chapter 210, Acts of 1891, as their recommendations and
suggestions.

WM. R. SESSIONS,

Secretary of the State Board of Agriculture.
BOSTON, Jan. 1, 1898.

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To the Massachusetts Slate Board of Agriculture.

Your committee, to which was committed the work of ex-
terminating the gypsy moth, under the orders of the Legislat-
ure, herewith presents the report of expenditures and of
work performed during the year 1897.

The balance on hand Jan. 1, 1897, as reported last year,
was $8,849.85. This balance was retained to enable the
committee to close up the work and turn over the material
on hand belonging to the State, without the necessity of a
deficiency appropriation, should the Legislature decide to
make no further appropriation. But, under the advice of
authorized State officers, the committee was led to conclude
that the work could be continued ' ' during the month of Jan-
uary, until the pleasure of the General Court should be made
known, at the rate of expenditure authorized by the appropri-
ation of the preceding year." In this way the committee
was enabled to avoid the discharge of the efficient men then
in its employ.

The Legislature acted promptly, and on February 26 ap-
propriated $150,000 for the work of 1897. This prompt
action, so different from past experience, was in a high
degree advantageous, as it enabled the committee to do an
immense amount of necessary work that could be done only
before the appearance of the young caterpillars in the spring.
The sum appropriated by the Legislature, however, was only
three-fourths of the amount estimated by the committee as
necessary for the effectual carrying on of the work required
by law. With only three-fourths of the required amount
available, the plans for the year were necessarily revised, and
much work that had been planned had to be abandoned
and must now be reported as still undone.

During the years 1895-96 most of the territory com-
prised in the infested towns had been quite carefully in-

10 THE GYPSY MOTH.

spected, and, as it was believed that no large unknown
colonies existed in the infested region, it was planned in
1897, first, to work thoroughly all known colonies, espe-
cially those in the Saugus woodlands. During January,
February, March and the first part of April the men were
employed in cutting underbrush and dead wood, and in
trimming and otherwise preparing the infested localities for
the work of the burlapping season. As soon as the appro-
priation became available the force was increased, so that
on April 1 three hundred and fifty- four men were in the
field. This force was largely employed during the first
part of April in continuing the cleaning up of infested
localities and destroying the eggs of the moth in wood-
land colonies, principally in Saugus and Medford. A sup-
ply of burlap was purchased, and during the latter part of
April and the month of May was put on the trees in most
of the known infested localities. While this was being

^3

done, the scattered eggs of the moth upon the ground in
the woodland commenced hatching and the caterpillars be-
gan ascending the trees. In some of the worst colonies,
where the undergrowth had been removed, the trees had
been previously banded with insect lime. In these places
the caterpillars were either destroyed by starvation or killed
by fire before they could ascend the trees. In other cases
spraying was resorted to. Arsenate of lead was the insecti-
cide principally used, and, though its effect was somewhat
neutralized by continuous wet weather, it greatly reduced
the number of caterpillars. During the summer the force
of men, which at one time numbered three hundred and
eighty-seven, was used almost entirely in attending the
burlaps. While the increase of the appropriation over that
of 1896 has enabled the committee in 1897 to clear away
the underbrush from the worst infested woodland colonies
and to destroy a large proportion of the caterpillars in the
Saugus woods, the legislative reduction of twenty-five per
cent, from the committee's estimate of $200,000 for 1897
has made it impossible to extend to all quarters the scheme
of work planned for the year ; hence the work in the Med-
ford woods (Middlesex Fells region) was not so complete
as that done in Saugus.

REPORT OF COMMITTEE. 11

The force of men was necessarily reduced in August by
the discharge of one hundred and twenty-five men, and all
work was suspended for two weeks in September, therefore
it was impossible to inspect thoroughly all of the colonies
when the burlap was taken off. The known colonies in the
Saugus woods were inspected in the latter part of Septem-
ber and in October, and the eggs on the trees destroyed.
This having been done, the men in that section were put
at work inspecting the known colonies in Lynnfield, Salem,
Marblehead, Swampscott and Peabody, and destroying the
few eggs which could be found in these towns. The rest
of the force was concentrated in the Middlesex Fells region,
in Medford, where the moths had been hardly held in check
by the work of the previous winter, spring and summer.
Here a force of ninety men was kept at work destroying
the eggs of the moth until December, when, the appropria-
tion having been nearly exhausted, a large proportion of the
men were discharged.

The result of the year's work is, that where there were
three badly infested colonies of a thousand acres each in the
woods of the infested region there now remains only one
such colony. In that one the increase of the moths has now
been checked, but they are more widely scattered there than
they were in 1896 ; therefore the cost of treating this Middle-
sex Fells region will be greater another year than it would
have been had sufficient means been provided in 1897 to
check the increase and spread of the moth there. The
known colonies in the outer towns have been attended to,
and their favorable condition, as reported last year, has
been maintained and in many instances improved. Only
one new point of infestation outside of last year's lines has
been discovered, and this place, situated in the town of
Lincoln, has been promptly and carefully attended to. It
was discovered in woodland at some distance from the high-
way. From all indications, it has been infested for several
years. It would have been found long before had sufficient
means been provided for a thorough inspection of all the
towns near the infested region .

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The reports of past years have stated that there were large
woodland colonies of the moth in the central part of the in-

12 THE GYPSY MOTH.

fested region, which, from lack of money, have necessarily
been neglected, in order to attend to the outer circle of in-
fested towns. In this outer circle the object has been to
reduce the area -infested and to prevent the moths spreading
into new territory, beyond the known line of infestation.
The committee has also reported that from the woodland
colonies, in the central towns, the moths would be liable to
spread into territory not previously infested and also into
the area that had been cleared of the moth. The woodland
in Medford, Maiden, Melrose, Winchester and Stoneham has
largely been taken for park purposes, and developed by the
construction of boulevards and roads for driving and bicy-
cling and paths for foot passengers ; in short, it has become
a place of resort for the people. Street-car lines have also
been constructed on roads passing through infested woods in
other towns. The result has been, as was predicted in former
reports, that the caterpillars have been brought out of these
woodland colonies on carriages and teams and on the clothing
of persons, and thus land already cleared at much labor and
expense has become reinfested. To prevent the neutralization
of exterminative work in this way, great efforts have been
made at large expense during the past year to suppress these
larger colonies. Vast quantities of eggs were destroyed
during the winter and early spring, large areas of woods and
brush were thinned out or cut down, and much laud was
burned over. The plan proposed by the committee in the
last report was to do this work and also continue the careful
inspection of the outside territory, i. e., that beyond the
outer circle of infested towns, as well as that formerly in-
fested but now thoroughly cleared. This plan has been fol-
lowed as closely as was possible with the amount of money
appropriated. But only three-quarters of the work planned
could be accomplished with three-fourths of the appropriation
asked for. The trees in the vicinity of all points where the
moths have been found in the outer towns within the past
three years have been burlapped and carefully attended.
This has served to verify the work of former years and to
show where that work was not absolutely completed, and has
also proved that caterpillars have, as was feared, been scat-
tered from the badly infested woodland colonies in the cen-

REPORT OF COMMITTEE. 13

tral towns into territory formerly cleared. The outer towns
are in good condition, and the burlap has proved our last
year's statement of the situation to have been correct in
nearly all cases. Had $200,000 been provided for the work
of the season of 1897, all the known colonies in the infested
region could have been cleaned up during the spring and
thoroughly worked during the summer. This would have
prevented the scattering of the moths from these badly in-
fested colonies into territory previously cleared ; the com-
mittee could have avoided the discharge of many experienced
and trustworthy men, and by retaining their services the
known infested localities could have been put in such ex-
cellent condition that in the work of 1898 the badly infested
colonies could have been attended to at less cost.

The work of the past few years has convinced the com-
mittee that extermination of the moth is not only possible,
but certain, if sufficient sums be promptly appropriated for
the purpose. The committee recommends that $200,000 be
appropriated for the work of 1898. While a larger sum
than that could now be used to advantage, the committee
believes that under the present conditions, with our experi-
enced and trained men, a long stride could be made with
that sum toward extermination. Most of the worst colonies
of the moth are now so reduced that with $200,000 they all
can be attended to and a reasonably thorough inspection
made of all the towns in the infested territory.

Unless the work above outlined can be done during 1898,
extermination will be gravely imperiled by reinfestation from
the central woodland colonies. Inadequate appropriations
necessitate doing the same work over and over, year after
year, with comparatively little progress toward extermi-
nation ; and the committee believes that, unless the neces-
sary means can be provided, the Legislature had better make
no appropriation, and so abandon the work.

The appropriation for 1897 is exhausted, and the com-
mittee hopes that the Legislature will act promptly, to save
the dispersion of the force, so that the work may go on
consecutively, and the loss be avoided which always comes
from cessation of work.

Interest in the extermination of the gypsy moth is wide-

14 THE GYPSY MOTH.

spread, particularly among economic entomologists and
agriculturists. Scientific men in most of the countries of
Europe have obtained the committee's reports and express
their approval of the work. Prominent journals in Europe
have published comprehensive reviews and discussions of
the work, in every case speaking of it favorably. The
economic entomologists of this country with one accord
express themselves as anxious that the work should be
continued, not only for the protection of the country from
a new imported pest, but as a demonstration of what gov-
ernment can do for the advantage of the people ; many of
them having stated that they believe it would be a public
calamity to have the work stopped.

At the National Farmers' Congress, held at St. Paul,
Aug. 31 to Sept. 1, 1897, the matter, as in former years,
was considered, and the following resolve adopted :

Resolved, That the efforts of the Commonwealth of Massachu-
setts in endeavoring to exterminate the imported pest known as
the gypsy moth meet with our hearty approval, and we, members
of the Farmers' National Congress, assembled at St. Paul, ear-
nestly appeal to the Congress of the United States to aid our sister
State in exterminating what is liable to prove a national pest if
neglected.

At the last meeting of the Association of Economic En-
tomologists, held in Detroit, Aug. 12 and 13, 1897, the fol-
lowing preamble and resolve were unanimously adopted :

Whereas, The Association of Economic Entomologists is famil-
iar with the efforts being made by the State of Massachusetts to
exterminate the gypsy moth ; and

Whereas, On two former occasions it has endorsed this under-
taking by public resolutions ; and

Whereas, The existence of the gypsy moth in Massachusetts is
a standing menace, not only to the agricultural and forestry in-
terests of that State but to those of the country at large ; there-
fore, be it

Resolved, That this association would urge upon the people of
Massachusetts the danger of dilatory measures, and the wisdom
and great importance of providing liberally for the work of ex-
terminating the gypsy moth.

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REPORT OF COMMITTEE. 15

In January, 1897, a careful inspection and investigation
of the exterininative work was made, under the auspices of
the Massachusetts Society for Promoting Agriculture, by
Prof. John B. Smith, entomologist of the New Jersey Ex-
periment Station. His report has been largely given to the
public through the press. In it he speaks in the highest
terms of the work of the committee, and expresses the
opinion that extermination is possible if sufficient means are
seasonably provided. He recommended that it would be
well to investigate the natural enemies of the gypsy moth in
Europe, with a view to introducing any insect enemy of the
moth that might be of advantage. While the members of
your committee consider the results of such an investigation
to be problematical, they will be ready at any time to carry
it out should the Legislature provide the means.

The entomologist of the United States Department of
Agriculture, under the instruction of Congress, has been
making an extended inspection of the work and an investiga-
tion of the methods in use. The report of his investigation
will very soon appear as a bulletin of the United States
Department of Agriculture.

Experiments have been continued in perfecting spraying
machinery and insecticides at the insectary in Maiden and
the experiment station at Arnherst. In addition to the
regular experimental work, a large number of injurious in-
sects, erroneously supposed to be the gypsy moth, which
were sent to the office of the committee by residents of the
infested region, have been identified and advice given con-
cerning remedies.

The committee desires in this connection to emphasize its
grateful appreciation of the value of the scientific work as
conducted by Prof. C. H. Fernald, entomologist of the
Board.

Reference is also made to the reports of Prof. C. H.
Fernald, entomologist, and E. H. Forbush, director, presented
herewith as a part of the report of the committee.

FINANCIAL REPORT FOR 1897.

The gypsy moth committee of the State Board of Agricult-
ure presents below its financial report for the year 1897 :

16 THE GYPSY MOTH.

Balance on hand Jan. 1, 1897, . .... $8,849 85

Appropriation Feb. 26, 1897, . . . 150,000 00

$158,849 85

Win. R. Sessions, expenses, . $20 25

E. W. Wood, expenses, . . 20 96
Augustus Pratt, expenses, . . . , 61 00

F. W. Sargent, expenses, .... 50 40
J. G. Avery, expenses, ..... 140 55
S. S. Stetson, expenses, .... 46 75
C. H. Fernald, expenses and remuneration, 561 29
E. H. Forbush, director, salary, . . 2,300 00
Travelling expenses of director and men, . 1,350 47
Teaming, livery and board of horses, . . 3,653 30

Wages of employees, 134,711 54

Rent of offices, 427 64

Supplies, tools, insecticides, etc., . . . 13,206 76

$156,550 91

Balance on hand Jan. 1, 1898, 2,298 94

$158,849 85

The balance indicated as on hand Jan. 1, 1898, will all or
nearly all be required to pay bills for labor, material and
running expenses already contracted ; hence the appropria-
tion must be regarded as practically exhausted.

E. W. WOOD,
S.'S. STETSON,
JOHN G. AVERY,
AUGUSTUS PRATT,

F. W. SARGENT,
WM. R. SESSIONS,

Committee of the Board of Agriculture in
Charge of the Gypsy Moth Work.

REPORT OF ENTOMOLOGIST. 17

REPORT OF THE ENTOMOLOGIS

To the Committee on the Gypsy Moth.

GENTLEMEN : The most important question arising in
connection with the work on the gypsy moth is whether it is
possible to exterminate the pest. If this can be done, there
is no question but that it is the wisest policy to continue the
work till the extermination of this insect is accomplished.
I have made frequent and careful examinations of the work
from the beginning, and have seen colony after colony ab-
solutely exterminated, some of them in localities where the
difficulties in the way appeared to be insurmountable and as
great as could be found anywhere, and yet the insect was
completely exterminated by the force under the oversight of
the field director. Not only have single colonies been ex-
terminated, but entire towns have been cleared and for several
years no gypsy moths have been found in them.

Several years ago all the leading economic entomologists
of the country were invited to inspect the work of extermina-
tion and report on the same. Some of these gentlemen before
visiting the territory expressed the opinion that this insect
could not be exterminated ; but, having made a careful study
of the territory, the apparatus and the methods of work,
they all became thoroughly convinced that extermination is
possible, provided sufficient money be appropriated for the
purpose. The reports of these gentlemen have been pub-
lished in previous gypsy moth reports. Last winter the
members of the Society for the Promotion of Agriculture
employed Prof. J. B. Smith of Rutgers College as an expert
to investigate the work and make a written report to them.
Professor Smith, who is undoubtedly one of the very highest
authorities on economic entomology, made a very careful
study of the infested territory, the methods of work, etc.,
spending nearly a week in his investigations, and came to

is THE GYPSY MOTH.

the conclusion emphatically that extermination is not only
possible but entirely practicable. The report of Professor
Smith was a masterly production, and I deeply regret that
the Society for the Promotion of Agriculture has not seen
fit to publish it.

Since all the experts who have carefully and fully investi-
gated the matter believe extermination to be possible, and,
as previously stated, we have already exterminated numerous
colonies, many of them in the most unfavorable places and
of considerable extent, there can be no question but that
what has been done in one place can be done in another,
and that the complete extermination of this insect is possi-
ble, so that the result is dependent entirely upon the action
of the Legislature.

I have no doubt that the gypsy moth would have been
practically exterminated by this time if the Legislature had
each year made the full appropriation asked for, and made
it available early in the season.

The next important question is, how long it will take to
complete the work of exterminating this pest and how much
it will cost. The estimate of time and money given in my
report of last year is as close an estimate as I can make at
this time, since we were not able during the past year to
make that progress in the work which we should have made
if the last Legislature had appropriated the full amount for
which the committee asked, instead of a much smaller sum.
That estimate was " an appropriation of not less than $200,-
000 a year for a term of not less than five years, and then
an appropriation of not less than $100,000 a year for a term
of not less than five years. After this an appropriation of
perhaps $15,000 a year for a period of five years will be
required." The first five years, with the full appropriation
of $200,000 a year, will reduce the territory to such an ex-
tent that with $100,000 a year for the next five years the
insect will be practically exterminated, and the remaining
five years will be spent in a careful watch of the entire ter-
ritory, lest a few insects might have been overlooked in
isolated localities. Unless a sufficient amount is appro-
priated to make a very substantial gain each year, it would
be better to abandon the work entirely.

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REPORT OF ENTOMOLOGIST. 19

The metropolitan park system in Boston and some of the
adjacent cities and towns is threatened by this insect, and,
in fact, the Middlesex Fells reservation belonging to this
system is already infested by the gypsy nioth. The ex-
pense of exterminating this insect in a public park is far
greater than from the same area of ordinary forest land,
for the reason that in the latter case all the shrubs, under-
brush and small trees can be cut down and burned, or, if
need be, the land can be entirely cleared and burned over;
while this course could not be adopted in a public park like
the Boston Common or Public Garden, or even in Franklin
Park or any portion of the metropolitan park system. If,
therefore, the State should abandon the work of extermi-
nating the gypsy moth, this insect would soon spread all over
these parks, and the tax payers of Boston would be per-
petually taxed for one-half of the expense of clearing the
moth from the metropolitan parks, while the other cities
and towns in the metropolitan district would pay the other
half, and Boston would be taxed for the entire expense of
the work in the Boston parks. I feel very sure that any
one who has had any considerable experience in the field
work on the gypsy moth would agree with me in the
opinion that the annual tax on the city of Boston and the
other towns of the district would then be far more than it
will be if the Legislature makes the necessary appropri-
ations for the extermination of this insect within the limits
of Massachusetts. And it must especially be remembered
that this question of gypsy moth extermination is by no
means mainly a local one.

Should the gypsy moth escape from control, as it
assuredly would do if the work of extermination were to
cease, it would spread in all directions, doing incalculable
damage over the whole State. Extermination would then be
impracticable, and a perpetual warfare against the rnoth-
most unsatisfactory in results, yet necessitating oppressive
expense to all time would then be entailed upon the people
of Massachusetts. The most economic policy for the tax
payers of Boston, as well as for the entire Commonwealth, is
to have the insect exterminated as soon as possible.

It is an unwise and dangerous policy to make smaller

->0 THE GYPSY MOTH.

appropriations than are necessary for a vigorous prosecution
of this work. The supposition that, as in many other public
works, a small appropriation will carry it on to a certain
point, and then, if left, it can be taken up again and carried
on from where the work left off, is an incorrect one, for the
reason that this insect is continually multiplying and spread-
ing when left to itself, and there is always the danger in such
times that it may be carried off accidentally along the lines
of travel to remote parts of this State or even into other
States. This insect will therefore be a constant menace to
us until it is absolutely exterminated from the land.

Respectfully submitted,

C. H. FERNALD.

REPORT OF DIRECTOR. 21

_ LI BR AR

.-*,

FIELD DIRECTOR'S REPORT

To the Committee on the Gypsy Moth.

GENTLEMEN : In submitting this report the director has
endeavored to comply with your recent request to present
(1) a brief report of the year's work and its results; (2) a
condensed report on the present condition of each infested
town or city ; (3) the causes which have led to the increase
of the gypsy moth in the central woodlands ; (4) a statement
showing how extermination can be accomplished in these
woodlands; (5) a record of the progress of extermination;
(6) the reasons why, if the gypsy moth is to be exterminated
from Massachusetts, larger appropriations must be granted.

THE WORK or THE WINTER AND SPRING.

In January and February, 1897, the force, numbering one
hundred and thirty-four men, was employed mainly in kill-
ing the eggs of the gypsy moth in the woodlands most in-
fested, in cutting worthless trees and in otherwise preparing
these woods for the summer work.

In addition to pushing exterminative work in all the known
colonies, it had been planned to make in 1897 an inspection,
wherever needed, of the entire infested territory ; but when
the desired appropriation for 1897 ($200,000) was cut down
by the Legislature to $150,000, this inspection was of neces-
sity given up.

The appropriation became available Feb. 26, 1897. The
force was then increased as rapidly as the preservation of its
effectiveness permitted, and was mainly concentrated in the
localities most infested. The largest force was massed in
Here and also in the Fells and Mystic w r oodland

22 THE GYPSY MOTH.

colonies-* work similar to that of January and February was
continued, weather permitting, well into the spring.! More
than one thousand acres were thus worked. The under-
growth of many colonies in the great pastures of Salem and
Swampscott was cut and burned. In former years this win-
ter and spring work of egg-killing and cleaning up has been
greatly hampered by delay in the legislative grants; this
year the granting of the appropriation at a comparatively
early date enabled this work to be much more thoroughly
done than it has ever been done before, and with correspond-
ingly satisfactory results.

EXPERIMENTS IN KILLING EGGS IN STONE WALLS.

The moths frequently assemble along stone walls. In past
years, when the eggs of the moth abounded in these walls,
the walls were torn down, and often had to be rebuilt at a
heavy cost. Most of this work has now been done away
with. When, in 1897, the young caterpillars hatching in a
wall congregated upon the shrubbery, close to either side of
it, they were destroyed in quantities, together with the shrub-
bery, by the use of the cyclone burner. Trees close to the
wall were cut away. If then any living caterpillars were left
they were forced to give up the wall as a gathering place (as
they then had to go some distance for food) , and were taken
later under burlaps on adjacent trees. In cases where full-
grown caterpillars resorted to a wall to pupate, they were
destroyed by driving the cyclone flame through it.

Experiments made by Assistant Entomologist Kirkland
prove that paraffin gas oil, a nearly crude petroleum oil, is
destructive, in temperate or warm w T eather, to gypsy moth
eggs. At the suggestion of Supt. C. S. Williams, experi-
ments were made in spraying certain stone walls with this

* Webster defines a colony (under the bead of natural bistory) as a number of
animals or plants living together beyond tbeir usual range. In the gypsy moth
work the word " colony " has been applied to the moth when it has been found iso-
lated from others of its kind by a belt of uninfested territory.

t The localities referred to here are three great groups of colonies, which have
been alluded to in former reports. These groups contain about one thousand acres
each. The Saugus colonies centre in the Saugus woods ; the Fells colonies, in the
Middlesex Fells ; the Mystic colonies, to the west of the Mystic lakes in the woods
of Arlington, Winchester, Lexington and Woburn.

BURLAPPING. 23

cheap crude oil, delivered from a cyclone burner, but not
ignited. The oil penetrated the crevices in the walls and
destroyed the eggs hidden there. These experiments were
so satisfactory that it will be desirable to continue them on

a larger scale.

BURLAPPING.

The early date when the appropriation became available
permitted the purchase of burlap in advance of the rise in
prices, caused by the new tariff. About one thousand dol-
lars was thus saved.

In April and May burlap was cut up, sent into the field
and applied to the trees in infested forest lands where the
underbrush had been cleared away. Throughout the whole
infested region the most work was done, in the burlap sea-
son, where the greatest number of caterpillars were known
to be. Every practicable effort was made, however, to
destroy, by burlapping, the few caterpillars still remaining
in colonies almost exterminated. This was especially the
case in the outer towns.

The unusual amount of rain in June seemed to interfere
with the movements of the caterpillars. In many of the
large colonies they remained mostly among the leaves and
branches, instead of coming down the trunks to the burlaps ;
therefore, during this month the burlaps were not so effective
as usual. In the Saugus woods the caterpillars were shaken
to the ground by jarring the trees. They would then crawl
up the tree trunks and crowd under the burlaps, where they
were crushed by the workers. Had not this method been
followed, the trees in many localities would have been com-
pletely stripped. Later, when the caterpillars were about
to pupate, they resumed their normal habits and crowded
under the burlaps. When the moths had all deposited their
eggs the burlaps were generally removed, and many eggs
clustered under or near them on the trees were destroyed.

SPRAYING.

During May and June rains unfortunately prevailed, inter-
fering seriously w r ith the spraying, which, however, so
decimated the caterpillars that, as a rule, the sprayed trees
were not stripped.

24 THE GYPSY MOTH.

Arsenate of barium, used in spraying somewhat more ex-
tensively than heretofore, proved less satisfactory than
arsenate of lead. This latter insecticide, when mixed with
sufficient glucose, maintained its superiority over all others.
The best results from spraying were obtained on under-
growth, shrubbery, hedges and low trees.

With the object of devising some mechanical means for
reaching the upper limbs of tall trees, models have been
made, and one machine has been constructed and actually
tested in the field. While it is not difficult to invent such a
machine to do effective work on level streets and lawns, no
device yet perfected can be used to advantage for spraying
tall trees, growing close together on our rugged hillsides.
Experiments looking to this end are still going on. Improve-
ments have also been made in hose, couplings, extension
poles, pumps and nozzles. A new set of spraying outfits is
now being constructed at the headquarters in Maiden.

WORK OF THE FALL AND WINTER.

On account of the rapid decrease of the appropriation, the
force was greatly reduced in August, and all work was sus-
pended for two weeks in September. On September 20 the
fall work was begun. Inspection and egg-killing were car-
ried on in all the known colonies in Saugus woods, and all
of those in the towns to the north and east of Saugus. When
this was finished the men employed in the eastern division
were concentrated in Saugus, where an inspection of the
residential portion of the town was begun, and this was
nearly finished when, the appropriation being nearly ex-
hausted, the men were discharged. In October a rapid in-
spection of Maiden, most of which could not lie burlapped
during the summer, was begun, and the greater part of the
eggs there were destroyed. Some of the nearly exterminated
woodland colonies in the outskirts of the western part of the
infested region were thoroughly examined, and some inspec-
tion was made of territory outside the limits of known in-
festation. Nearly three-fourths of the men were then con-
centrated and employed in egg-killing in the Middlesex Fells
region. Early in December, the appropriation being nearly
expended, the work was stopped ; therefore, although

THE YEAR'S WORK. L>;>

enormous quantities of the eggs of the ruoth were destroyed
in these woods in November, nearly all the good weather of
December was lost. This was a great misfortune, for it has
left this excellent work but little more than half done, and it
will now be a difficult task to complete it before the eggs
hatch in the spring.

SUMMARY OF THE YEAR'S WORK.

The figures given below represent such proportion of a
year's work as can be accurately tabulated. The trees were
mainly cut on the 1,010 acres of laud, where the under-
brush was cut and burned. The buildings, fences and other
structures which are reported as infested were merely har-
boring or hiding places of the moth. Usuallv the eo-o-s

/ J?C

were found upon, about or underneath these structures.

It will be noticed that no figures giving the number of
the trees found infested or the numbers of the different
forms of the moth destroyed appear in these tables. This
may be explained as follows :

Every effort has been made in the field work to economize
time and material, wherever it could be done without inter-
fering with the efficiency of the work. In woodlands most
infested, especially in the Middlesex Fells region, only
enough trees were marked to indicate the presence of the
moth. This was a great saving of time and white paint,
but it made a correct record of the number of trees found
infested in these colonies a practical impossibility. Where
only one tree in twenty was marked as infested during 1897,
no accurate account of infested trees could be made. This
invalidated the entire record of infested trees, and the time
ordinarily taken to count and record them has been saved.

The record of the number of caterpillars and other forms
of the moth taken is not given, for in one or two of the
most densely infested localities the caterpillars were found
in such masses that any attempt to count them would have
been a great waste of time. Furthermore, it was necessary
to destroy them immediately, to prevent their spreading.
In many other colonies spraying was almost entirely de-
pended upon to destroy the caterpillars. In other cases
spraying and fire were used to destroy the caterpillars and

26 THE GYPSY MOTH.

the eggs. Many trees were cut down and burned with the
eggs upon them. Therefore the number of different forms
of the moth destroyed during the year cannot be correctly
stated ; but the records of moths killed in the outer towns
are very accurate, and enough has been learned from the
figures taken to show that approximately ninety-live per
cent of the different forms of the moth were killed in Med-
ford and Saugus woods and in adjacent territory.

Work Done.

Trees (fruit, shade and forest) :

Inspected (number of times), 12,202,692

Burlapped, . . ... 1,117,628

Banded with insect lime, 4,715

In which cavities have been cemented or covered, . . 1,949

Sprayed, 21,479

Scraped, ... 1,401

Trimmed, 81,545

Trimmed for burlap, 39,615

Cut, 279,101

Cutting and burning :

Acres of brush and shrubbery cut and burned, . . . 1,010

Acres of ground burned over with oil, 62

Acres of ground burned over without oil, . . . 122

Buildings :

Inspected, 12,998

Found to be infested, 1,138

Wooden fences :

Inspected (rods), . 72,652

Found to be infested, 1,150

Stone walls :

Inspected (rods), 18,534

Found to be infested, 596

Burned out (rods), 1,683

False Alarms.

During 1897, as in former years, reports of the presence
of supposed gypsy moths or of injury caused by them have

been received from towns within the infested region and

o

from other towns in the State ; but in no such case has any
evidence of the moth been found by our investigation outside
of the region previously known to be infested, except in
Lincoln.

NUMBER OF EMPLOYEES.

27

Towns and Cities that have been falsely reported as infested by the

Gypsy Moth in 1897.

Barnstable,

Methuen,

Wellesley,

Danvers,

Natick,

Wenham.

Dennis,
Fitchburg,
Haverhill,

Newton,
Plympton,
Quincy,

Hebron, N. H.
Haverhill, N. H.

NUMBER or EMPLOYEES IN 1897.

The figures given below do not fully represent the number
of employees on the pay roll, which at the height of the
season reached nearly four hundred, but give the number of
those actually at work each week :

Jan 1-Jan. 2,

. 134

June 28 -July 3,

. 352

Jan 4- Jan 9,

. 133

July 5-July 10, .

. 343

Jan. 11- Jan. 16,

. 135

July 12-July 17, .

. 339

Jan. 18-Jan. 23, .

. 144

July 19-July 24, .

. 333

Jan. 25 -Jan. 30,

. 144

July 26 -July 31, .

. 328

Feb 1-Feb 6,

. 150

Aug. 2-Aug. 7,

. 324

Feb. 8-Feb. 13, .

. 151

Aug. 9 -Aug. 14, .

. 324

Feb. 15-Feb. 20, .

. 151

Aug. 16-Aug. 21, .

. 207

Feb 22-Feb. 27, .

. 152

Aug. 23-Aug. 28, .

. 204

March 1-March 6,

. 164

Aug. 30-Sept. 4, .

. 202

March 8-March 13,

. 164

Sept 20-Sept. 25, .

. 201

March 15-March 20,

. 249

Sept. 27-Oct. 2, .

. 188

March 22-March 27,

. 249

Oct 4 -Oct. 9,

. 188

March 29-April 3,

. 354

Oct. 11-Oct. 16, .

. 189

April 5-April 10, .

. 354

Oct. 18-Oct. 23, .

. 184

April 12-April 17,

. 368

Oct. 25 -Oct. 30, .

. 184

April 19-April 24,

. 383

Nov. 1-Nov. 6,

. 182

April 26-May 1, .

. 370

Nov. 8 -Nov. 13, .

. 183

May 3-May 8,

. 371

Nov. 15-Nov. 20, .

. 183

May 10 -May 15, .

. 371

Nov 22-Nov. 27, .

. 179

May 17-May 22, .

. 360

Nov. 29 -Dec. 4, .

. 175

May 23-May 29, .

. 360

Dec. 6-Dec. 11, .

. 173

May 31-June 5,

. 361

Dec 13-Dec. 18, .

. 29

June 7-June 12, =

. 353

Dec. 20-Dec 25, ,

. 29

June 14 -June 19, .

. 353

Dec. 27-Dec. 31, .

. 48

June 21 -June 26, =

. 352

L'-S THE GYPSY MOTH.

THE PRESENT CONDITION OF THE INFESTED REGION.

To give an absolutely accurate report of the condition of
the infested territory is impossible, unless the whole region
has been gone over within the year. The report given below
indicates mainly the condition of the known colonies. For
the following reasons the clearing of the moth from any new
towns cannot this year be reported :

1. Because of insufficient means, the greater part of the
work had to be confined to the central tow r ns (more especially
within the Middlesex Fells and the Saugus woods), where it
was of the first importance to prevent, by a general destruc-
tion of the moths, their conveyance from these central colo-
nies back into territory wholly or nearly cleared.

2. There has been during the year no thorough inspec-
tion of all the territory of the outer infested towns.

Arlington.

The condition of Arlington appears better than at any
time since the work was begun in 1891. Only a few cater-
pillars were found in 1897, in the most easterly part of the
town. The wooded section in the northern portion, in which
some of the worst infested colonies have been found since
1891, was burlapped during the^ summer and inspected.
Although the number of men which could be spared for the
work was inadequate, the condition of this woodland is now
greatly improved. Comparatively few egg-clusters have been
found there. Only one of the woodland colonies appeared
to be much infested in 1897, and but few caterpillars have
been found elsewhere in the Arlington woods this year.*
Many of the estates formerly infested have produced no moths
this year, and only here and there along the roads have
occasional moths been found. A few orchards are still con-
siderably infested. Little except burlapping and other nec-
essary summer work in known infested localities has been
done in Arlington for the past three years. It is some time
since the entire town was thoroughly inspected. In 1897,
however, most of the town was covered either during the
burlapping season or afterward.

* The phrase " this year," as used in this report, refers exclusively to 1897.

THE INFESTED REGION.

Belmont.

In many of the old colonies in Belmont no form of the
gypsy moth has been found for two or three years, In these
colonies the moth has been, no doubt, exterminated. Al-
though in the infested places and their vicinity the trees have
been well burlapped and carefully watched during the sum-
mer, very few caterpillars have been found except in the hill
section to the west of the centre of the town. Here, among
the shrubbery and trees on several highly cultivated and
valuable estates, a good many caterpillars were taken. On
the north side of the town, along both sides of Pleasant
Street, several farms are still somewhat infested, and there
are also a few small colonies near the Cambridge line ; else-
where the town contains few moths, so far as known. A few
egg-clusters were found in the fall in the Beaver Brook reser-
vation of the metropolitan park system, near the Walthaui
line.

Beverly.

No gypsy moths have been found in Beverly for the past
two years. All the known colonies appear to have been
exterminated.

Boston.

At Orient Heights, East Boston, 577 caterpillars were
found early in the season. In all the colonies in the remain-
der of Boston, including Charlestown, South Boston, Dor-
chester, Roxbury, West Roxbury and Brighton, only 195
caterpillars were taken, The trees in the East Boston colony
were climbed and carefully looked over in the latter part of
the summer, and no form of the moth was found at this in-
spection.

South Boston as a whole has had no tree-to-tree inspection
for the past few years. The only colony there known to be
infested was burlapped this year, and 42 caterpillars were
found. Nothing has been done there since the burlappiug
season. The place should, if possible, have an inspection in
1898. Only 1 caterpillar was found in the Roxbury district
in 1897. No moths were found in Franklin Park this year,
although a thorough inspection was made of a greater part
of the park. This still further connrrns the belief that Frank-

30 THE GYPSY MOTH.

lin Park is now free from the moth. In 1897 no moths were
found in Charlestown ; 1 caterpillar was found in Brighton,
at a place where a large number of teams are stabled. In
Dorchester, where 18 bushels of caterpillars were gathered in
1895, only 151 caterpillars were found in 1897.

Brookline.

The two colonies which were found in Brookline in 1896
were quite thorougkly burlapped that season. A few hidden
e^ffs had hatched in 1897 in each of these colonies before the

^^^?

spring inspection was finished. In one, however, the cater-
pillars were all destroyed early in the season. In the other
all were, apparently, destroyed, except in that part of the
colony where the inspection and cleaning up was not finished
in the spring. There the most of the caterpillars were killed
and a few egg-clusters were destroyed in the fall, The clean-
ing up of this colony was not finished when the men were
laid off in December.

A careful survey of the boundary between Newton and
Brookline shows that two trees (formerly, but not now, in-
fested) included in one of the Brookline colonies stand just
over the line in Newton. A search made in the fall in the
northern part of Newton, adjoining Brookline, resulted in
the discovery of a male pupa case of the gypsy moth . This
discovery is not regarded as significant, but, since Newton
borders on the infested region, the city should be carefully
watched.

Burlington.

In the colony reported last year as infested a few caterpil-
lars were found in 1897. Altogether 9 caterpillars, 1 pupa
and 3 egg-clusters were found in the town. From a small
colony in Woburn, near the Burlington line, a few stragglers
crossed into Burlington, which accounts for two of these egg-
clusters. The continued infestation of Burlington is readily
traceable to large teaming operations conducted by one man.

Cambridge.

The tree-to-tree inspection of Cambridge, which was begun
in 1896, had to be given up in 1897, in common with other
work, on account of the reduction of the appropriation ;

THE INFESTED REGION.

therefore only about one-fourth of the city was inspected in
this manner. All the known colonies were burlapped and
carefully looked after during the summer. Most of the old
colonies appear to have been exterminated before 1897.
There are still some in which a few caterpillars were found.
Only 3 caterpillars were killed in North Cambridge, in a lo-
cality where some years since 35,000 egg-clusters were de-
stroyed within a week. There are a few places in Cambridge
where numbers of caterpillars were taken. On some of these
estates the trees and shrubbery are of such historic value that
it is not advisable to destroy them ; thus extermination is
rendered extremely difficult. The discovery of single cater-
pillars here and there under the burlap indicates that they are
scattering into Cambridge from the central towns.

Chelsea.

In the southern half of the city only a single pupa was
found in 1897. Here all the trees in the immediate vicinity
of the colonies infested in 1895 were burlapped and care-
fully looked over. In the northern half of the city cater-
pillars were found in ten localities. Later in the season a
new colony was found on a dumping ground, among some
low bushes. Here 2,016 pupse were found; 94 egg-clusters
were also destroyed at the last of the burlapping season.

As Chelsea has in the past been generally infested, and in
some sections the moth has been very numerous indeed, the
good condition indicated by this report is remarkable.

The entire city had a tree-to-tree examination in 1895,
and was quite thoroughly burlapped in 1894 and 1895 ; but,
as Chelsea is immediately adjacent to Everett and quite near
Maiden, it is to be expected that caterpillars will be carried
there through the ordinary channels of traffic and travel so
long as these cities remain uncleared.

Danvers.

Gypsy moths have not been found in Danvers within the
past three years. The places formerly infested have been
examined ; but, on account of the traffic between it and the
infested towns and also between it and Boston, another in-
spection soon is desirable.

32 THE GYPSY MOTH.

Everett.

Most of the trees in Everett were burlapped in 1897 and
the burlaps attended ; although the moths are still widely
distributed through the city, considerable progress has been
made since 1896. In that year 4(32,477 caterpillars were
taken under the burlap. In 1897 only 152,202 were taken
in the same manner. A thorough inspection of the city
should now be made, and all the eggs killed before hatching
time.

Lexington.

The colonies formerly known in East Lexington and
Lexington Centre, on both sides of Massachusetts Avenue,
are now apparently exterminated. This appears to be true
also of the scattered colonies on the farms, for in most of
these no caterpillars have been found during the summer.
Only 3 caterpillars have been found on Massachusetts
avenue during the summer, where formerly many thou-
sands were found. The large woodland colonies in the
eastern part of the town, formerly so badly infested, are
now in far better condition. One tract of about twenty
acres has been cut off by the owners and burned over by
your agents. No caterpillars have been found since on
this tract. Much of the adjacent woodland, which in the
past has been considerably infested, has been burned over
by forest fires. Infested portions of this woodland have
been burlapped and inspected during the summer, and in
nearly all of them but few caterpillars have been found.
The fall inspection has revealed but few egg-clusters. Only
one of the large wood colonies in the north of Lexington
has been found infested this year, and in that only 101
caterpillars were killed on a few trees.

The town had a tree-to-tree inspection in 1895 ; since
that time all the colonies which had not then been exter-
minated have been very carefully worked.

Lincoln.

July 13, 1897, a colony was reported from Lincoln. It
was situated less than a mile from the boundary of Waltham,
the nearest town in the infested region as heretofore known.

THE INFESTED REGION. 33

Here the caterpillars had already stripped the trees on about
a half acre of ground in the edge of a strip of woodland,
and many were travelling north and east across a grass-
grown field, eating the grass as they went. The owner,
seeing there were two or three caterpillars on each stalk
of grass, immediately cut it and saved part of the crop.
The owner of the woodland set men at work {ratherin^

o o

the caterpillars and pupae in baskets, and burning them in

fires built for that purpose. Your agents were soon on
the ground, and began destroying the caterpillars with the
cyclone burner. They were swept and shaken from the
trees and burned, until few could be found in the centre
of the colony. In the meantime, those in the field had left
the grass as soon as it began to dry in the sun, and, crossing
the field, swarmed into the trees and undergrowth on a
wooded hillside. Here their progress was arrested by the
cyclone burner.

An inspection of the country in the vicinity was begun
in August. As the colony was near the southern boundary
of Lincoln, the northern part of Weston, which adjoins
Lincoln, was inspected, but no indications of the moth
were found there. In a later inspection of the territory
immediately about the colony a few egg-clusters were found
just over the Lincoln line in Weston. Continued inspec-
tion has enlarged the known area of the colony, and it is
now known that the moths are scattered half a mile to
the north and east from the centre. This inspection was
brought to a close by the cessation of field work in Decem-
ber, and should be finished as soon in 1898 as the weather
conditions will permit. The vast number of caterpillars
found here, their distribution over so large a territory, and
other signs of long occupation, all indicate that the colony
has been established for several years. The owner of the
infested property has lived in Cambridge during the winters,
and has driven back and forth in the summers when the
gypsy moth was most numerous in that city. In all prob-
ability this colony was established at that time, or before the
work of exterminating the gypsy moth was begun. The
situation of the colony at some distance from the main road
explains why it was not found in the roadside inspection of
Lincoln made some years ago. Had it been possible earlier

34 THE GYPSY MOTH.

to make a tree-to-tree inspection of Lincoln and the other
towns around the boundary of the infested region, this
colony would long since have been discovered.

Lynn.

Previous to 1897 more than 1,200 estates in the city
proper had been found infested ; but this year 7 caterpillars,
found on seven widely scattered trees, a few caterpillars
killed in another locality and a few egg-clusters found in
the fall inspection, constitute all the finds recorded. The
known colonies in the Lynn woods have been very much
improved in condition, and some of them have been nearly
if not quite exterminated this year. The chief difficulty in
exterminating the moth from this great forest park is that it
is not advisable to use there ' those drastic and sweeping
measures which are so effectual in woodland colonies.
Nevertheless, as the moths are decreasing year by year,
it seems probable that they can be exterminated from the
Lynn woods by the methods now in use. Owing to a lack
of means, a large portion of this woodland has not been
examined for several years. Although no colonies are known
in that portion, its nearness to the badly infested Saugus
woods makes it probable that small colonies will be found
there on inspection.

Lynnfield.

All the colonies discovered in 1891-92 in the orchards
and along the roads of Lynnfield were exterminated three
years ago. A later inspection of the woods resulted in the
discovery of a considerable number of large and dangerous
colonies. The work of the last three years has much
reduced these colonies, and some of them now appear to be
exterminated. This is true also of one discovered in the
woods of northern Lynnfield, near the Heading line, in
1896. Two colonies recently found on the roads have been
carefully worked this year, but will need to be watched for
at least two seasons. There were found under the burlap in
Lynnfield, in 1896, 15,084 caterpillars and 22,022 pupa ; in
1897 the burlapping was more extended, but only 194 cater-
pillars and 81 pupse were found.

THE INFESTED REGION. 35

Maiden.

It was reported in 1896 that for several years very little
injury had been done by the gypsy moths to the foliage in
Maiden. Still less injury was done in 1897, but, as only a
small portion of the city was burlapped, the moths increased
in number considerably during the summer. Most of the
city was rapidly gone over in the fall, and all the eggs seen
in this rapid inspection were destroyed. Although the eggs
are not now very numerous anywhere, the city is, as last
year, generally infested, and it is probable that no advance
toward extermination has been made in Maiden by the work
of this season. Situated in the centre of the infested region,
Maiden has been perforce neglected. Most of the trees
should be burlapped in 1898, and everything possible should
now be done to exterminate the moth there, as otherwise it
cannot be prevented from spreading into the neighboring
towns.

Marblehead.

The gypsy moth has been found in 1897 in only one local-
ity in Marblehead. This colony was mentioned in the last
annual report. All eggs which could be found were de-
stroyed in the spring. The eggs were distributed along a
stone wall overgrown with underbrush, and a few caterpillars
hatched from scattered eggs in the wall and from eggs hidden
in hollow trees. The undergrowth along the wall was then
burned and the trees burlapped. Only two egg-clusters were
found in the fall. The entire town had a tree-to-tree inspec-
tion in 1896-97. It now needs an occasional inspection to
prevent its becoming reinfested.

Medford.

Medford, where the moth was first introduced into this
country, is situated near the centre of the infested district,
and is now, as in 1891, the place most infested of all the
region. The centre of infestation, however, has changed from

<_ ' O

the residential and business portion, in which much restric-
tive work has been done, to the woodlands of the Middlesex
Fells. There the moth has hardly been held in check by all

36 THE GYPSY MOTH.

the work which could, under the circumstances, be done.
More egg-clusters still remain there than are to be found
anywhere else in the infested region. Those sections of the
city where the moths were known to be most numerous, in-
cluding the Middlesex Fells colonies, were burlapped in the
spring. These burlaps were as well attended as could be
expected by the twenty-five men allotted to Medford. Al-
though the work done during the summer failed to hold the
moth in check in the woods, it kept the borders of the wood-
land roads quite clear from the pest, and there were only two
or three localities where the trees were stripped. The con-
centration of nearly three-fourths of the entire force in these
woods during October and November has made it possible to
put them in better condition than they otherwise would have
been, but there are several colonies in which the eggs on the
trees have not yet been destroyed. This work and that of
preparing the woodland colonies for the work of next sum-
mer would employ 100 men from Jan. 1, 1898, to the hatch-
ing season, while burlapping, spraying, egg-killing and other
absolutely necessary work would keep them very busy for
the remainder of the year.

i

Melrose.

The northern half of Melrose was burlapped in 1896 and
1897. Few caterpillars were found in 1897. South of the
centre of the town no work was done in 1896, except an in-
spection of the residential part in the fall. This part of the
town was, however, burlapped in 1897. It was found that
the number of the moths had increased considerably, espe-
cially in the woodlands near the Maiden line ; but their num-
ber was greatly reduced by the work of the burlap season.
Effective work was done in several colonies in that part of
Melrose which is located in the Middlesex Fells reservation,
and on the later inspections of the burlaps few caterpillars
were found. The general condition of the town is now better
than in any previous year. In many of the places now
marked as infested only single caterpillars were taken. The
position of the town, lying, as it does, with the badly in-
fested woods of Saugus on the east, Maiden on the south and

THE INFESTED REGION. 37

the Middlesex Fells on the west, will render it impossible to
keep the moths out so long as they are numerous in the ad-
jacent woodlands.

Nahant.

No gypsy moths have been found in Nahant for more than
two years.

Peabody.

The gypsy moth is believed to be exterminated from all
the old infested localities in the centre of Peabody, and in
only three of the woodland colonies have moths been found
this year. In one of these, 1 caterpillar was found ; in an-
other, only 2. The third the large woodland colony in
the vicinity of Spring Pond which has been so badly infested
in years past appears now to be cleared of the moth ; but,
on account of its extent, and the fact that caterpillars were
found there this year, it must be carefully watched for at
least two years. In 1896, 129,408 caterpillars and 379 pupa
were taken there; in 1897, only 458 caterpillars and 14
pupse were taken. In the summer a colony was found in the
central part of the town, which had become infested since
any work had been done there. This colony has since been
cleaned, but will require careful watching another year.

The reduction in the number of the different forms of the
moth found in Peabody indicates that a great improvement
has been made in the town.

Reading.

In 1896 no living form of the moth was found in Reading,
but in the winter of 1896-97 one hatched egg-cluster and one
dead pupa were found on a farm north of the centre of the
town. This place was burlapped in the summer of 1897,
and 10 caterpillars and 13 pupae were found there. No form
of the moth was found elsewhere in Reading.

Revere.

The only considerable tract of woodland in Revere adjoins
Maiden and Saugus, and is situated near Franklin Park.
This tract had never been thoroughly worked over until

38 THE GYPSY MOTH.

1897, and it was here that most of the moths found were
killed. These woods became infested because of their near-
ness to infested woods just over the line in Saugus and Mai-
den. "Early in the season this tract was looked over and a
considerable portion of the underbrush cut out and burned.
The trees were burlapped and attended through the summer.
Although the town has had no inspection during the fall,
winter or spring for several years, most of the residential
portions, including all the known colonies outside of the
woodland before mentioned, were gone over -either in 1895
or 1896, and for three years nearly all the trees in town
have been burlapped each summer and well attended, so that
it has been kept in excellent condition ; but its situation is
close to the central infested towns, and thousands of people
travel from them to the Revere beaches during the summer.

^

On this account the moth will probably be found in Revere
so long as the central towns continue to be infested.

Salem.

All but two of the old colonies in the business and residential
part of Salem appear to have been exterminated. In one of
these colonies all the eggs which were found in the winter
of 1896-97 were destroyed. In the summer of 1897 cater-
pillars were taken here. In the fall inspection two egg-
clusters were found in the other colony.

In the Salem pastures many colonies of gypsy moths have
formerly been found. The vegetation on this tract consists
largely of red cedar interspersed with hard-wood trees, and
the ground is overgrown with barberry bushes and ground

v O

juniper. The density of this growth renders a thorough
search for eggs impossible, but the young caterpillars can
readily be found on the low foliage. A search of a large
portion of the pastures was made during the spring, and
wherever caterpillars were found most of the trees were cut
and the ground and undergrowth burned over with oil.
Apparently this has exterminated the caterpillars from most
of these pasture colonies ; but this region will need a careful
watching for some years.

Most of the different forms of the moth found in Salem in
1897 were taken in the pastures.

THE INFESTED REGION. 39

Saugus.

In years past a number of rnoth colonies have been found
in the villages of Saugus and along the roads. These were
worked and closely watched for two or three years. A later
discovery of the woodland colonies made it necessary to devote
to the woodland much of the time formerly given to the vil-
lages. Notwithstanding the 'best use that could be made of
that part of the appropriation which could be apportioned to
Saugus, the woodland colonies have been extending until
1897, when the exigencies of the work necessitated the mass-
ing of about one hundred men in Saugus for several months.
Nearlv all of the infested woods were cleared of underbrush

V

and the dead trees cut out. In some of the worst colonies
the live trees were thinned out ; in others, the owners cut
the wood and the ground wag j- aen cleared and burned over.

^2

Most of the colonies were thoroughly burlapped. This bur-
lapping was followed up during the summer, with the result
that the moths are now nearly exterminated from several of
these colonies, and the improvement in the condition of
nearly all of them is remarkable. For example, in the five
worst colonies 437,150 egg-clusters laid in 1896 and only
40,457 egg-clusters laid in 1897 were taken. There is a
portion of the Saugus woodland which has not been inspected
for years. This should be inspected during the winter of
1897-98, and any colonies found should be cleared up and
thoroughly worked. Another year of such work as has been
done in Saugus in 1897 should bring all the large colonies
which have been worked this year very near to extermination.

Somerville.

The good condition of Somerville, as reported last year,
has been maintained and somewhat improved so far as the
known colonies are concerned. There are a few localities in
which the moth still hangs on. Only 1,047 caterpillars were
taken in the city in the summer of 1897. On account of the
proximity of Medford, Somerville must be carefully watched
and inspected to prevent reiufestation.

Hemlock killed by the gypsy moth in the Saugus woods.

THE INFESTED REGION. 41

Wakefield.

In 1896 the number of known colonies in Wakefield had
been reduced to five. In 1897 no moths were found in two
of these, but one of the colonies in Saugus woods has ex-
tended over the line into Wakefield, and some thousands
of caterpillars were taken there.

As all the old colonies in the central and northern part
of the town had been exterminated some years since, there
has been very little work done there since 1894, when a
tree-to-tree inspection of the whole town was made. An
examination of the centre of the town was made by one
man in November, 1897, and two egg-clusters were found.

Watertown.

The last inspection was begun here in 1896 and finished
in 1897, when one small colony was found. This will re-
quire to be watched another year. Outside of this colony
the moths were found in Mt. Auburn cemetery only, which
is partially in Cambridge.

Winchester.

In the residential and business portions of Winchester
few gypsy moths were found in 1897. In many of the
village estates that have been found infested this year,
only one, two or three caterpillars have been found. The
caterpillars have been most numerous on the farms in the
outskirts of the town, especially in the orchards and woods
in the western and southern sections, adjoining Lexington,
Arlington and Medford. The worst infested of these wood-
land districts were cleared of underbrush in the winter of
1896-97 and the following spring, and burlapped. In two
or three of the colonies large numbers of the caterpillars
were killed, and the numbers of the moths greatly reduced,
so that now very few eggs can be found there. In other
colonies where many caterpillars were killed in 1895-96
very few were found in 1897. In one of the worst colonies
33 acres of woodland were cut by the owners and the
underbrush was burned. Wherever, in this tract, cater-
pillars were found in the spring, the ground and sprouts

42 THE GYPSY MOTH.

were burned over, and no evidence of the inoth has been
discovered on this ground since. In another colony, in
which caterpillars have been abundant during the past two
summers, your agents cut off the wood from about ten
acres. The ground here was burned over wherever cater-
pillars appeared in the spring, and only two egg-clusters
have been found in this lot since the burning. In the

O

south-eastern portion of the town, bordering on the Middle-
sex Fells reservation, is a tract of farm land where there
have been strips of badly infested woodland. Most of this
was cut or cleared up in the spring of 1897, and vast num-
bers of the eggs were destroyed by fire. This work and
the burlapping of the summer has greatly reduced the
moths in this section and prevented their distribution to
other parts of the town.

Although Winchester has been more carefully examined
during the burlap season than last year, the number of cater-
pillars killed was much smaller. The numbers killed were
as follows: in 1896, 243,639; in 1897, 130,221.

Most of Winchester has been inspected quite thoroughly
within three years, either in the burlapping season or during
the fall, winter and spring.

As a whole, Winchester is now in better condition with
regard to the gypsy moth than it has been at any time dur-
ing the past few years.

Winthrop.

All the colonies in Winthrop in which any form of the
moth was found in 1896 were burlapped in 1897. The trees
were climbed and carefully inspected. Only 23 caterpillars
and 3 pupte were found. An inspection of the infested locali-
ties was made when the burlap was taken off, but no eggs
were found. The entire town was very thoroughly inspected
in 1896, and nearly all the trees in the town were burlapped
for three years in succession. The results reached are largely
due to a liberal use of burlap. The moth appears to be
nearly exterminated from Winthrop, but, as there is much
driving there during the summer from Maiden, Medford and
other infested towns, it is probable a few caterpillars will be
distributed there annually so long as they are to be found in
numbers in these central towns.

THE INFESTED KEGION. 43

Woburn.

In the residential and business parts of Woburn only a few
scattering caterpillars were found here and there during the

O C

summer of 1897, with the exception of two localities, where
new colonies were discovered in the spring about the time
the eggs were hatching. These colonies were thoroughly
treated by fire and followed up by burlapping. Another
season they will require only careful watching and burlap-
ping. On account of the discovery of these colonies, the
number of caterpillars taken in AY o burn this year was prac-
tically the same as the number taken last year. In the wood-
land, in the south-west corner of the city, where the largest
colonies of the moth had been found in past years, the cut-
ting and burning of infested wood and brush have been ex-
tended to the Winchester line. No moths have been found
on this tract since. Two wood lots near the Lexington line
have also been cut, and no doubt this and other measures
will eventually result in the extermination of the moth in

/

that section. The single isolated caterpillars found indicate
that they have been redistributed in Woburn during the past
summer by such means as originally infested the town. If
the moths can now be exterminated from the badly infested
centres in the inner towns, which are now reinvesting Woburn
and the other outer towns, there will be no difficulty in
clearing Woburn of the gypsy moth within a short time.

THE INCREASE or THE MOTH ix THE CENTRAL WOODLANDS.

It becomes necessary now to revert to the history of the
efforts to exterminate the gypsy moth in former years.

In 1892 your committee ascertained, and then duly re-
ported, that at least 400 acres of central woodland were
known to be more or less infested by the gypsy moth, and
asked for means sufficient to stamp out the moth from these
forested tracts. Furthermore, your committee predicted
that, in case sufficient appropriations were not granted,
there would be great danger that the insect might extend
its hold in these woodlands, with the result that it might
be much more difficult to secure its extirpation. Means
adequate for the purpose were not then nor afterwards
granted.

44 THE GYPSY MOTH.

Your committee has from year to year, as in duty bound,
reported that an alarming increase and spread of the moth
was progressing in these woodlands, in spite of all the work
that could be done to check it with manifestly insufficient
appropriations.

In 1895 your committee ascertained and duly reported
that the forest infestation of 1892 (400 acres) had increased
to 3,000 acres. The increased appropriation granted in
1895 made possible the cleaning up of a small pail of
these woodlands ; but, as the appropriation was greatly
reduced and delayed again in 1896, much of the advan-
tage gained by the work done in 1895 was lost. At least
2,000 acres of these woods were found in the winter of
1896-97 to be in a worse condition than ever before. Had
this increase and spread been allowed to go on in 1897, no
doubt the cost of the necessary exterminative work in these
woodlands in 1898 would have been greater than that of
handling the colonies in all the rest of the infested region,
and in fact greater than any annual appropriation which has
thus far been granted.

METHODS OF EXTERMINATION IN WOODLANDS.
It was long since proved that the gypsy moth could
readily be exterminated from open and cultivated lauds,
orchards and shade trees ; it has now been abundantly
shown that it can be exterminated from the woods. In
forest park lands, where it is not advisable to cut away
or burn trees, shrubbery and vines, progress has been
necessarily slow ; but in ordinary woodland extermination
has progressed more rapidly. In some cases the wood was
cut off by the owner, and, after undergoing a sufficient
quarantine, was marketed by him. The brush was then
burned, the land cleaned up and the ground burned over.
In other cases, where the land was sparsely wooded and
more or less grown up to underbrush, it was cleared and
burned over. Where the land was valuable for prospective
building purposes, it was burned over and nearly cleared,
leaving a few of the finer shade trees only, thus greatly
reducing the number of trees to be afterwards burlapped
and inspected. In other cases the number of trees was

PROGRESS OF EXTERMINATION. 45

V

reduced by cutting out only the worthless trees, and the
ground cleaned up by removing and burning the under-
brush. In certain colonies where the moth had appeared
in many thousands, the eggs on the trees were destroyed
and the ground burned over with oil. Later the trees were
banded with Raupenleiin, to prevent the caterpillars ascend-
ing, and the few caterpillars which hatched from the eggs
remaining on the ground were thus starved. Any one of
these methods will bring about extermination, if supple-
mented by such others as can be used to the best advantage.
Extermination here, as elsewhere, must be verified through
several years by a thorough search in the summer for the
caterpillars and in the winter for the eggs of the moth.

THE PROGRESS OF EXTERMINATION.

All practical entomologists who have followed the work of
extermination for the past six or seven years are now con-
vinced that the gypsy moth can be exterminated, and that its
extermination, under the present methods, is only a question
of time and adequate appropriations. People who hold op-
posite opinions seem to be impressed by the belief that the
gypsy moth is generally distributed over the whole so-called
infested territory of more than 200 square miles. This, em-
phatically, is not the case, nor has it ever been the case.
Outside the central towns the moth is found only in isolated
swarms or colonies, separated by wide intervals of uninfested
ground. In fact, the greater part of the region called in-
fested has never been invaded by the moth. For this reason
it is never necessary to make a careful, thorough search over
all the territory of the towns in the infested region, for the
purpose of discovering single caterpillars or moths. Such
scrupulous searching is essential only in and around the
known colonies. In seeking for and destroying the moth in
these colonies, the greater part of the appropriation has al-
ways been expended, and must always be, so long as the
moths are numerous. But there should also be, from time to
time, a rather rapid search of all the region between the col-
onies. This should be conducted in the fall, winter and
early spring, when deciduous trees bear little or no foli-
age, to provide against the establishment of new colonies.

46 THE GYPSY MOTH.

This search over the entire country is what is called a tree-
to-tree examination, and is made, not to find the last cater-
pillar or the last moth, but to find the last colony. When
that is found, careful inspection, burning, spraying, burlap-
ping and other means must be utilized to destroy the last
moth in that locality.

When any given locality has been apparently freed from
the moth, extermination there must be verified by careful
examinations for a term of years before it can be authorita-
tively announced.

The methods now in use have always exterminated the
moth wherever they have been followed without interruption
for a reasonable period. A personal examination of the
colonies known to have been infested in 1897 leads to the
conclusion that much more progress toward extermination
has been made this year than in any previous season. Out-
side the Fells region, except in Maiden and Medford, the
condition of nearly all the known colonies has been greatly
improved by the work of 1897. Against this favorable state-
ment must be set the fact that less inspection than usual has
been made in 1897, except in or near the vicinity of the
known colonies. The residential and business sections of
several of the outer towns were, however, burlapped almost
entirely this year, and the burlap carefully inspected. This
resulted in the picking up of a stray caterpillar here and there
on territory not lately infested. The discovery of such strays
does not indicate the local hatching of even a single esrs:-
cluster, but rather demonstrates that the caterpillars have
been disseminated by vehicles and pedestrians within the
past two years from the large colonies (especially the wood-
land colonies) in the central towns into territory previously
cleared. But, it may be asked, why was not the moth eradi-
cated from these central woodlands while the colonies there
were still small, and, therefore, comparatively easy to exter-
minate? This was not done for the reason that before it
could be attempted there were discovered in the woodlands
of the outer towns larger colonies which were then in worse
condition than were those in the inner towns. As money
enough had not been provided to attend to all, it became
necessary to attend to the outer towns first, on account of

LARGE APPROPRIATIONS NEEDED. 47

their position near the border of the infested region. The
first duty of the committee, under the law, was to " prevent
the spreading" of the gypsy moth; and there was evidently
more danger then of the moths spreading from these outer
colonies into territory outside the infested region than there
was of their spreading into this outside territory from the
forest colonies in the central towns.

In summing up the progress of extermination, it may be
fairly stated that in the outer two-thirds of the district
known as the infested region there remain now only a few
known colonies, most of which are on the verge of extermi-
nation. From this portion of the infested region the moth
now appears to be almost, if not quite, exterminated.

The problem of extermination is now considerably simpli-
fied. The large colonies in the woodlands of the outer
towns have been either exterminated or so reduced that their
extermination is a matter of a short time. Serious danger
from this source of the conveyance of the moth into towns
beyond the border of the infested region has been eliminated.
It is true that the large woodland colonies in the Fells are
not improved. But a large force of men, which has hereto-
fore been of necessity scattered in isolated colonies in the
outer towns, can now be concentrated nearer the centre of
the infested region, in the Fells and Saugus colonies, and' in
Maiden, Medford and Everett, where the work can be more
economically supervised and directed.

LARGER APPROPRIATIONS ARE NEEDED.

As it has been already stated that progress has been made
with past appropriations, the question may well be asked,
Why, then, are larger appropriations now required? It may
be answered in brief that we have now reached a time when
much more rapid progress must be made, or the success of
the whole work will be put in imminent peril. This is clear
for the following, among other reasons :

1. A vast amount of work is immediately required in the
central woodlands, where, otherwise, the area now occupied
by the moth will greatly increase each year, thereby either
greatly increasing the final cost of extermination, or, by the

48 THE GYPSY MOTH.

enormous expense involved, compelling the abandonment of
the whole exterminative work.

2. The increased danger of disseminating the moth, due
to the constant opening to travel of new paths, parkways,
boulevards and trolley lines, leading into and through these
woodlands, also makes immediate extermination necessary
there.

3. If extermination in these woodlands is to succeed, it
must be begun at once, and on a large scale. The work must
be of the most thorough nature, and it must be followed up
throughout every month of the year.

4. Much of this woodland has been taken for metropolitan
or municipal parks ; other large portions are highly valued
for prospective building purposes. While cutting and burn-
ing all the trees on these forested lands might be in the end
the most economical course, such measures need hardly be
considered in the case of public parks ; there less drastic
methods are recommended. If the trees are to be generally
preserved there, and it seems that they must be, the extermi-
nation of the moth from these lands will be extremely ex-
pensive. With larger appropriations in the past, advantage
could have been taken of the favorable conditions then exist-
ing. The moth could have been readily and rapidly exter-
minated from the colonies, then comparatively very small, in
the central woodlands, and thus, of course, prevented from
spreading over the large tracts it now occupies. A great
deal of money would thus have been saved in the end.

5. The reduction of past appropriations and the delay in
making them has necessitated a repetition of merely partial
work year after year in many colonies, deferring their exter-
mination and increasing its ultimate cost three to ten times.
The force in not a few instances has been compelled to skip
from one part of the territory to another, much as if a fire
department, in attempting to control a tierce conflagration
with an insufficient number of men, should run about from
one outbreak to another, completely subduing none. Under
this policy the moth has increased and spread in every place
which has been for the time necessarily neglected.

6. Experience demonstrates that the moth colonies can-
not be exterminated in detail. On the contrary, if extermi-
nation is to succeed, every effort must be made each year to

LARGE APPROPRIATIONS NEEDED. 49

exterminate all these colonies simultaneously. In the fall
of 1897, as in previous years, much work had to be left un-
done, in order that the most dangerous colonies might be
looked to. To do the required work in the Middlesex Fells,
it was necessary to neglect for two months all the outer and
intermediate colonies in two-thirds of the infested reo-iou.

o

It will require a large sum of money to thoroughly inspect
these colonies, and destroy, before hatching time, the few
egg-clusters still remaining there. To do the required work
in the generally infested central woodland and residential
territory in Medford, Melrose, Maiden, Everett and Saugus,
with portions of contiguous towns, will cost a larger sum
than has hitherto been used in any year in the entire infested
territory.

7. The moth, within the last three years, has shown
alarming evidence of increased vigor and fertility, and has
suffered little perceptible check from its parasitic or other
natural enemies. Unless the moth is stamped out promptly,
circumstances favorable to its still further increase may arise.

8. The discovery within the last two years of three colo-
nies of the moth outside of what has been known as the in-
fested region, emphasizes the necessity of another and more
thorough examination of all the towns bordering upon it.
If an undiscovered extra limital colony has already become
established near the infested region, a thorough examination

o o

of a belt, two towns wide, outside the boundary of known
infestation, would bring it to light. Such an inspection,
covering the greater part of 1898 and the two following
years, ought to be made. Its cost would be heavy.

CONCLUSION.

If, through further reduced and delayed appropriations,
the moths in the central woodlands should be allowed to
increase in numbers and spread over more territory, even
though they might be so well held in check there as for a time
to do no appreciable injury, it would be but a few years
before the annual cost of exterminative work in the woods
alone would be greater than all the money heretofore ex-
pended in the entire region. It must be borne in mind, too,
that, if the central woods are now to be cleared, the residen-
tial parts of the towns and cities immediately adjoining these

50 THE GYPSY MOTH.

woods must also be promptly cleared of the moth, in order
that infestation may not be carried thence again into the
cleared areas both of forest and open country. The money
which has been thus far expended in the extermination of the
gypsy moth has accomplished much by protecting the or-
chards, gardens and forests of the infested region, and pre-
venting the spread of the moth throughout the State. It has
furnished an object lesson to the citizens who would have to
deal with the pest should the Commonwealth fail to support
the work. But, if extermination should be further delayed
by insufficient support, the money already expended will
have been thrown away, so far as accomplishing the end
in view is concerned, and in all probability the moth will
again occupy, not only the region from which it has been
cleared, but in due time the entire State also, from which
it will doubtless spread over the United States.

In short, the situation is this : in the outer towns, where
extermination has been pushed, it has succeeded ; in the
central towns, where, because of insufficient means, sup-
pression only could be tried, it has failed. Not only has
this enforced policy of mere suppression in the centre re-
sulted in failure, but it has also allowed the moth to spread,
thus jeopardizing again the outer towns. It is plain that
the only way to prevent the spread of the moth is to ex-
terminate it from the land. Further appropriations can be
justified only by a supreme effort to exterminate. No further
progress in extermination in toto is now possible with an
appropriation of less than $200,000. With the large num-
ber of experienced men now available, even a larger sum
could be used to advantage in 1898. It would be better to

o

give up the work now than to continue it with insufficient
appropriations, for in either case the moth will eventually
escape and spread over the country. If Massachusetts has
not the 1 .energy to crush this potent foe to agriculture and
forestry while she now has it in the hollow of her hand, if
she cannot now provide ample appropriations for this pur-
pose, then let not another dollar be expended.

Respectfully submitted,

E. H. FORBUSH.

APPENDIX.

The following papers represent as much of the scientific part of the
work for the extermination of the gypsy moth during the past year
as has been completed and prepared for publication. The gypsy moth
committee have held very broad and comprehensive views concerning
both the scientific investigations and the field work, for they recognize
the fact that all possible discoveries bearing on the destruction of this
insect pest should be made and given to the public. This very wise
policy has received the highest commendation from leading scientific
men both in this country and in Europe.

C. H. FERNALD.

U R A

ARSENATE OF LEAD AS AN INSECTI-
CIDE.

C. H. FERNALD, ENTOMOLOGIST.

In the work of destroying the gypsy moth it was soon
discovered that Paris green would not kill many of the cater-
pillars, even when used in as large a proportion in water as
was possible without injury to the foliage of the trees. It
therefore seemed necessary to discover, if possible, some
insecticide that would destroy the caterpillars and at the same
time not injure the most delicate foliage. Mr. F. C. Moul-
ton, who was employed by the gypsy moth committee as
chemist, was directed to investigate the various compounds
of arsenic, and endeavor to find some substitute for the insecr
ticides then in use which possessed the necessary proper-
ties. After a long series of experiments, in 1892 he was so
fortunate as to discover arsenate of lead, which certainly
possesses the desirable characteristics more fully than any
insecticide previously known.

The first public mention of arsenate of lead was made in
the report of the Massachusetts Agricultural College, Octo-
ber, 1893, p. 23. In Bulletin No. 24 of the Hatch Experi-
ment Station, Arnherst, Mass., published in April, 1894, a
more complete account was given of this insecticide and of
experiments with it on the tent caterpillar and Colorado
potato beetle. Mention was also made of this insecticide
under the name of " gypsine " in the report of the gypsy
moth committee for 1894, pp. 20 and 35. The name "gyp-
sine" was given to this insecticide by Mr. Moulton, but, as
there was an entirely different product on the market by the
same name, this insecticide was called arseuate of lead, to
avoid confusion. In the report of the gypsy moth commit-
tee, February, 1894, p. 20, the announcement of the dis-
covery of arsenate of lead by F. C. Moultou was made by
Mr. E. H. Forbush, the field director, and the formula was
given. In the same year Prof. James Fletcher, in " Evi-

54 THE GYPSY MOTH APPENDIX.

clence before the Standing Committee on Agriculture/' in
the Canadian Parliament, pp. 19 and 20, referred to this new
insecticide ; and again in the report of the Entomological
Society of Ontario, p. 71 (1894), he referred to its value.
In the seventh annual report of the Vermont Agricultural
Experiment Station, p. 123 (1894), Dr. G. H. Perkins, the
entomologist, recommended the use of arsenate of lead for
the destruction of several different kinds of insects, and
gave the formula for making it.

Arsenate of lead was described by Mr. E. H. Forbush,

*/

with its effects, value and limitations, in the report of the
gypsy moth committee for 1895, p. 1G. Mr. C. P. Loans-
bury, in Bulletin No. 28 of the Hatch Experiment Station,
p. 9 (1895), recommended this insecticide for the destruc-
tion of canker worms. In the Massachusetts Crop Report
of June, 1895, Mr. A. H. Kirkland gave a general descrip-
tion of arsenate of lead, its cost, etc. In the fifteenth
annual report of the New Jersey State Agricultural Experi-
ment Station, p. 400 (1895), Prof. J. B. Smith described
arsenate of lead, and recommended it highly for use against
the elm-leaf beetle. In the "Proceedings of the Association
of Economic Entomologists," p. 24 (1895), Mr. C. L. Mar-
latt gave an account of this insecticide, with a formula for
its preparation furnished by Mr. K. P. McElroy of the
Division of Chemistry of the Department of Agriculture,
Washington, D. C.

A more complete account of arsenate of lead, with the his-
tory of its discovery, uses and numerous experiments per-
formed with it, was given in "The Gypsy Moth," by Forbush
andFernald, pp. 69^80, 87, 142, 143, 145,449-473 (1896),
and Mr. Forbush gave an account of its use on hedges in the
report of the gypsy moth committee, p. 18 (1896). In Bul-
letin No. 36 of the Hatch Experiment Station, p. 6 (1896),
Mr. R. A. Cooley recommended the use of this insecticide
against the elm-leaf beetle. In the same year Prof. J. B.
Smith, in his "Economic Entomology," p. 436, described and
recommended arsenate of lead as an insecticide for leaf-eating
insects. In the " Proceedings of the Association of Eco-

O

nomic Entomologists" for 1896, p. 27, Mr. A. H. Kirkland
gave an account of arsenate of lead ; and in the same volume,
p. 44, Prof. J. B. Smith referred to the ease with which this

ARSENATE OF LEAD. 55

insecticide is prepared. In the proceedings of the same
society for 1897, p. 4G, Mr. Kirkland gave a full account of
the use of arsenate of lead against the gypsy moth.

This insecticide is easily prepared by putting 11 ounces
of acetate of lead in 4 quarts of water in a wooden pail, and
4 ounces of arsenate of soda (50 per cent.) in 2 quarts of
water in another wooden pail, and when entirely dissolved
mixing them in a hogshead containing 150 o-allons of water,

o ~ o o

when a chemical reaction will take place, forming arseuate
of lead as a fine white powder in suspension in the water.
If cold water be used, the solution of the acetate of lead
will require a little time ; but, however, if the water be hot,
it will dissolve very quickly. It is customary to add from
2 to 4 quarts of glucose to the above amount of water.
If it is desired to use larger proportions of the arsenate of
lead, it is only necessary to use more acetate of lead and
arsenate of soda, but in the proportions given above. A
more detailed and exact explanation is given in a following
paper by Mr. F. J. Smith.

Arsenate of lead has already proved to be the most val-
uable insecticide known for the destruction of the gypsy
moth. It does not injure the foliage of the most delicate
plants, even when used in as large a proportion as 25 pounds,
or even more, to 150 gallons of water; in fact, there is no
known arsenical insecticide so harmless to vegetation as arse-
nate of lead. This substance remains in suspension in water
much longer than Paris green, because of its very low spe-
cific gravity, which is 1.00668, while that of Paris green is
3.42225. In spraying, the low specific gravity of arsenate
of lead and its consequent suspension in water for a consider-
able length of time make it possible to distribute it more
evenly over vegetation. The white color is also a decided
advantage, for one is able to see at a glance whether a tree
or shrub has been sprayed; and it is a noteworthy fact that.
this insecticide adheres to the foliage far longer than any
similar substance now in use.

What has been said with regard to the value of this insec-
ticide for the destruction of the gypsy moth is also true in
the case of other leaf-eating insects. In every case where
we ourselves have performed experiments on these insects,
and in all cases reported by others who appear to understand

56 THE GYPSY MOTH APPENDIX.

the use of it, the most satisfactory results have been ob-
tained. It is undoubtedly true that larger proportions of
this substance must be used than of Paris green, but this can
be done with entire safety to the vegetation. The cost of
the insecticide forms a very small part of the cost of spray-
ing ; and since arsenate of lead remains on the foliage so
much longer than other insecticides, a much larger pro-
portion can be used and even then be much cheaper than
(substances which wash off readily in showers, making it
necessary to spray the trees a second time.

A large percentage of the spraying done in orchards at the
present time is with a mixture of an insecticide and a fungi-
cide ; because, as has already been said, the great expense is
in the labor, and not in the materials used ; and when the
insecticide and fungicide can be applied together, the cost of
one spraying is saved. We have not experimented as yet
with a fungicide mixed with arsenate of lead, but our chem-
ist, Mr. F. J. Smith, informs me that he does not think there
will be any reaction between arsenate of lead and the Bor-
deaux mixture to prevent using them together, but that they
may be mixed and used as readily as Paris green and the
Bordeaux mixture. Professor Craig, in his report as hor-
ticulturist of the Experimental Farms, 1895, p. 119, records
excellent results with arsenate of lead against the codling

~ o

moth, and also good success in using the insecticide and

O O

Bordeaux mixture together.

Spraying may almost be regarded as a fine art. Not every
one of those even w 7 ho have had a long experience at the
work can spray a tree properly. I have repeatedly examined
trees which had been sprayed by those who considered them-
selves experienced hands at the work, and found the leaves
so wet that the water was dripping from them or standing on
the surface in such quantity that the poison was settling on
the lower part, where it either ran off, or, when the water
evaporated, the poison was confined to a fractional portion
of the leaf. Spraying should be done with a nozzle that
gives only a fine, mist-like spray, and should be stopped
before it runs on the leaves. This is more easily said than
done, but we often find men who seem to catch the idea, and
stop at the exact time.

ARSENATE OE LEAD. 57

ARSENATE OF LEAD: ITS MANUFACT-
URE AND CHEMICAL COMPOSITION.

FREDERIC J. SMITH, M.S., CHEMIST TO THE COMMITTEE.

The value of arsenate of lead as an insecticide has been
fully set forth in the preceding paper by the entomologist.
Since this insecticide has come into such o- e n e ral use, the

O

present seems a proper time to place on record the essential
facts concerning the ingredients used in making arsenate of
lead, the chemical reactions that are involved and the exact
composition of the final product. The results of our work
will, it is hoped, be all the more serviceable to economic
entomologists because it is apparent that the preparation
of this substance has not been generally understood, as is
shown by several erroneous and conflicting statements which
have been published concerning this subject.

To be exact, the arsenate of lead used in spraying oper-
ations is not a salt whose composition may be definitely
expressed by a single formula, but instead is a mixture of
both di-plumbic and tri-plunibic arsenates, the relative quan-
tities of each depending principally upon the source of the
soluble lead salt used. Since the term "arsenate of lead"
has now become so well established, it will be used in its
general sense in the present paper.

INGREDIEXTS.

Theoretically, in the preparation of arsenate of lead it is
only necessary to form a chemical union between the com-
mon lead oxide (litharge), PbO, and arsenic pentoxide,
As. 2 O 5 ; but, in order to obtain a product suitable for use as
an insecticide, the chemical union must take place between
soluble salts containing these oxides. In general practice,
arsenate of lead suitable for spraying purposes is prepared
by bringing together commercial grades of acetate or nitrate

58 THE GYPSY MOTH- -APPENDIX.

of lead and arsenate of soda. Owing to the variable com-
position of these commercial salts, a chemical analysis of
each is indispensable, as indicating the relative amounts to
be used. All such calculations must be based upon the
quantity of lead oxide (PbO) found in the lead salt and that
of arsenic pentoxide (As 2 O s ) contained in the arsenate of
soda, making due allowance for other acidulous radicals
which may precipitate the lead.

Both the acetate and the nitrate of lead are extensively
used in paint and dyeing industries, and especially as mor-
dants in calico printing. Arsenate of soda is chiefly used
to remove mordants.

Acetate of Lead, Lead Acetate, Sugar of Lead.

Pb(C 2 H 3 O,),3H,0.

So far as is known to the writer, this salt is the one gen-
erally used as a source of soluble lead oxide for the prepara-
tion of arsenate of lead. Acetate of lead may be obtained
in the market in all grades, from clear, transparent crystals
to dark gray or brown lumps, and is usually quite free from
adulteration. It is prepared either by exposing litharge
(PbO) to the action of the vapors of pyroligneous acid,
or by dissolving metallic lead in pyroligneous acid and re-
crystallizing the products from water solutions. Pure lead
acetate crystallizes in four-sided prisms, containing three
molecules of water of crystallization. Crystals formed by
the sudden cooling of a hot saturated water solution sepa-
rate in a more finely divided condition than those formed by
a slow evaporation. The finer crystals are especially desir-
able when the salt is to be used for technical purposes, or
when it is necessary to dissolve a large quantity in a short
space of time.

When the crystallized salt is exposed to the action of the
air there is a rapid loss of water of crystallization (efflores-
cence) and also a slow formation of lead carbonate, due to the
action of carbon di-oxide contained in the air. Thus the
percentage composition of crystallized lead acetate may be
materially changed. Loss of weight by efflorescence yields
a product containing a higher percentage of actual lead
acetate than the original crystallized salt, accompanied by

ARSENATE OF LEAD.

59

an increase of insoluble lead carbonate. The increase in the
percentage of lead acetate that accompanies efflorescence is
well illustrated by sample No. 4 of Table No. 1. Pure crys-
tallized lead acetate contains 58.81 per cent, of lead oxide;
but this sample, which had been exposed to the air in a
loosely covered vessel for over six months previous to analy-
sis, yielded 66.795 per cent, of lead oxide. The folio wing-
table indicates the amounts of available lead oxide contained
in different market grades of acetate of lead :

Table No. 1.

SAMPLE.

Percentage of

Lead Oxide

(PbO).

No. 1, crystallized acetate lead, from drug store, . . 59.525

No. 2, crystallized acetate lead, from drug store, . . 61.548

No. 3, crystallized acetate lead, from drug store, . . 60.650

No. 4, crystallized acetate lead (effloresced), . . . 66.795

No. 5, " chemically pure white acetate lead powder," from 62.500

wholesale chemist.

No. 6, "white acetate lead granulated," from wholesale 60.800

chemist.

No. 7, " white acetate lead lumps," from wholesale chemist, 60.550

No. 8, "brown acetate lead," from wholesale chemist, . 62.290

Samples Nos. 1, 2 and 3 were supposed to be chemically
pure. No. 4 has been previously described. No. 5 is some-
what more expensive than the other market grades, is in
a very finely divided condition and dissolves very readily in
water. No. 6 is the grade used last year by the gypsy moth
committee for the preparation of arsenate of lead. This
salt contains many lumps, which consist of finely divided
crystals. These lumps dissolve readily in cold water. No.
7 dissolves slowly in cold water, but easily in hot water.
No. 8 contains a considerable amount of tarry matters and a
small quantity of basic acetate of lead. In handling any of
these salts, proper care should be taken to avoid inhaling
their dust. Lead is a " cumulative" poison, and when once
absorbed is with difficulty eliminated from the system.

60 THE GYPSY MOTH APPENDIX.

Nitrate of Lead, Lead Nitrate, Lead Saltpetre.

Pb(N0 3 ) 2 .

The comparative cheapness of this salt first suggested its
possible value for the preparation of arsenate of lead. Ex-
periments made during the summer of 1897 indicate that
arsenate of lead prepared from the nitrate also possesses
properties quite as important as the lower market price of
the latter salt. The grade of this salt most common in the
market varies somewhat in its chemical composition. It is
prepared by dissolving "lead scale "or litharge (PbO) in
hot dilute nitric acid; upon evaporation, the nitrate of lead
crystallizes out in transparent octohedral crystals. Lead
nitrate has the advantage of containing a high percentage of
lead oxide. In the reaction between lead and nitric acid
there is a tendency toward the formation of basic salts, and

\J

the commercial lead nitrate usually contains a higher per-
centage of lead oxide than the chemically pure crystals.
Lead nitrate is not affected by exposure to the air, and does
not dissolve in water as readily as the acetate. The results
obtained from the analyses of three samples of lead nitrate
are o-iven in the following table :

^ O

Table No. 2.

SAMPLE.

Percentage of

Lead Oxide

(PbO).

No. 1, nitrate of lead, from drug store,
No. 2, nitrate of lead, from drug store,
No. 3, nitrate of lead, from wholesale chemist,

68.37
67.76

66.37

Arsenate of Soda, Arseniate of Soda, Di-sodic Arsenate,
Hydrodi-sodium Arsenate.

Na 2 HAs0 4 (H,O) D .

Aside from the mono-metallic arsenates, the soluble salts
of arsenic acid are limited to those of the alkaline metals.
Of the latter, the arsenates of potash and ammonium are

ARSENATE OF LEAD. 61

rarely met with, and have but a limited use in medicine ;
while sodium arsenate, from its abundance in the market and
low cost, is the only one that may be profitably considered
as a source of soluble arsenic acid. Several grades of this
salt, containing from 50 to 75 per cent, of arsenate of soda,
are found in the market.

The sodium arsenate of commerce was formerly prepared
by dissolving common white arsenic in a hot solution of
caustic soda, with the addition of a sufficient quantity of
sodium nitrate, the whole being evaporated to dry ness and
fused, when the sodium arsenite became oxidized to sodium
arsenate. At the present time, commercial arsenate of soda
is chiefly produced as a secondary product of the German
aniline industries. I ani informed by Mr. John S. Rigby,
F.R.S., of Liverpool, that English manufacturers of sul-
phuric acid are now using white arsenic in the place of
sulphuric acid for decomposing nitrate of soda in the nitre
pots, and are thus producing arsenate of soda as a by-
product.

The pure crystallized salt sold by druggists is prepared by
dissolving the crude arsenate of soda in water and concen-
trating the solution, when di-sodium arsenate having the
formula NagHAsO^HgO crystallizes out.

Pure di-sodium arsenate is isomorphous with di-sodium
phosphate, and possesses almost identical physical and chem-
ical properties. Under ordinary conditions di-sodium phos-
phate crystallizes with 12 molecules of water, but di-sodium
arsenate crystallizes with 12 molecules of water only when
the solution is evaporated and crystallized below the tem-
perature of 18 C. (Fresenius, J. pr. Chemie 56, 30.) In
discussing the preparation of arsenate of lead Mr. K. P.
McElroy unfortunately overlooked the fact that the arsenate
of soda containing 12 molecules of water is quite unsuitable
for the purpose, and hence the directions given by him
("Proceedings of the Association of Economic Entomolo-
gists," 1895, p. 24) are misleading. The amount of water
in the commercial salt is dependent upon its manner of
preparation and care in storage. All the commercial grades
contain less water of crystallization than the crystallized
salt, Na. 2 HAsO 4 7H 2 O, commonly sold by druggists, and when

62

THE GYPSY MOTH APPENDIX.

the composition of the commercial salt is expressed as a
formula, the water present may be written as (H 2 O) n , where
n = the number of molecules of water.

The most economical grades of arsenate of soda for the
preparation of arsenate of lead are those containing the
highest percentage of arsenic pentoxide, As 2 O 5 , and the least
amounts of chlorine and other foreign substances. A high
percentage of arsenic acid alone is not necessarily indicative
of the purity or value of the salt. The great variation in
the composition of the different grades of arsenate of soda
is exhibited in Table No. 3, and is probably due to different
processes of manufacture, and possibly, in the case of the
first sample, to adulteration with salt (NaCl).

Table No. 3.

CONSTITUENTS.

Sample No. 1.

Sample No. 2.

Water at 200 C.,

Per Cent.

7.73

Per Cent.

26.72

Chlorine,

17.81

2.60

Arsenic pentoxide (As., O 5 ),

39.69

45.39

Sodium oxide,

14.03

15.07

Sodium as chloride, .....

11.54

1.70

Potassium oxide,

6.02

7.63

Insoluble matter,

1.87

.19

Sulphates and nitrates (estimated),

1.31

.70

100.00

100.00

Sample No. 1 is known to the trade as "50 per cent,
arsenate soda," and is sold at a lower price than the " 65 per
cent, arsenate soda" represented by sample No. 2. For the
preparation of arsenate of lead it will suffice to determine
the amounts of arsenic pentoxide and chlorine present in
the arsenate of soda. Determinations made from four repre-
sentative samples of arsenate of soda follow :

ARSENATE OF LEAD.

Table No. 4.

SAMPLE.

Arsenic
Pentoxide.

Chlorine.

No.

3, chemically pure crystals, from drug store, .

Per Cent.

36.86

Per Cent.

No.

4, chemically pure crystals, from drug store,

36.77

-

No.

5, commercial, 58 to 60 per cent.,

37.70

.75

No.

7, commercial, 68 to 70 per cent.,

47.80

.57

The Presence of Chlorine in Ar senate of Soda.*
There are probably no commercial grades of arsenate
of soda wholly free from chlorine but its presence to the
amount of 2 or 3 per cent, does no serious harm. If chlorine
be present to a greater extent than 4 or 5 per cent., upon
the addition of the soluble lead salt to the impure arsenate
of soda a considerable quantity of chloride of lead will be
precipitated. This but wastes the soluble lead salt, since
chloride of lead has practically no value as an insecticide.
The reaction in this case may be expressed by the following
equation :

The solubility of lead chloride in water at 20 C. is .9712
part to 100 (Formanck), and in hot water 1 part to 22
(Wittstein).f The arsenate of lead should be precipitated
in a dilute solution, and where possible, brook or hydrant
water should be used in preference to colder spring or well
water.

Arsenate of Lead, Lead Arsenate.

Arsenate of lead may be prepared by mixing a solution of
arsenate of soda with a solution containing either acetate
or nitrate of lead. As previously stated, it consists of a

* Several other impurities, such as arsenious acid, sulphates, nitrates, etc., also
occur in commercial arsenate of soda. The arsenious acid, upon the addition of a
soluble lead salt, is precipitated as arsenite of lead, which possesses considerable
value as an insecticide.

t A. M. Corney, "Dictionary of Chemical Solubilities," 1896, p. 206.

64 THE GYPSY MOTH APPENDIX.

mixture of the di-plumbic and tri-plunibic arsenates, their
relative proportions varying according to the conditions of
temperature and concentration at the moment of precipi-
tation .

Where the acetate of lead is used approximately, the whole
of the arsenate of lead product consists of tri-plunibic arsen-
ate, as indicated by the following reaction :

3Pb(C 2 H 3 O 2 ) 2 3H 2 O4-2Na 2 HAsO 4 (H 2 O) n :=
Pb 3 (AsO 4 ) 2 +4NaC 2 H 3 2 +2C 2 H 4 O 2 + n (H 2 0).

In order to prepare arsenate of lead successfully, great care
must be taken to establish an exact ratio between the quan-
tities of the soluble lead and arsenic salts, otherwise injury
to the foliage may result. The reaction between acetate of
lead and arsenate of soda may be summarized as follows :

3PbO + As 2 O 5 Pb 3 (AsO 4 ) 2 .

One part Pb 3 (AsO 4 ) 2 requires .74416 part PbO and
.25584 part A& 2 O 5 . Experience has shown that it is advis-
able to increase the amount of lead oxide to .77812, in order
to insure an excess of lead. A single example will suffice to
show how the relative amounts of soluble lead and arsenic
salts may be fixed.

Let it be required to prepare 1 pound of arsenate of lead
from samples of lead acetate (X) and sodium arsenate (Y),
containing respectively 60 per cent, lead oxide (PbO) and
40 per cent, arsenic pentoxicle

Xr=: - 1 . 2969 pounds lead acetate.
.60

25584

Y = - = . 6396 pound arsenate of soda .
.40

Should the arsenate of soda contain 7 per cent, chlorine,
in addition to the arsenic pentoxide, there would be required
an additional amount of lead acetate (Z) to complete the
reaction between the two salts. One part chlorine is equiv-
alent to 3.1408 parts PbO, and the amount of lead acetate
required is determined as follows :

.6396 X.07X 3.1408
.60

AR8ENATE OF LEAD. 65

Adding the values of X and Z, we find that 1.5312 pounds
lead acetate are required for the reaction with .6396 pound
arsenate of soda of the grade specified. Expressing these
quantities in avoirdupois weights, 1 pound arsenate lead re-
quires 1 pound 84- ounces acetate of lead and 10^ ounces
arsenate soda.

The following equation represents the reaction between
arsenate of soda and nitrate of lead :

5Pb(NO 3 ) 2 +4Na 2 HAsO 4 (H 2 O) n

Pb s (AsO 4 ) 2 + 2PbHAsO 4 + 8XaNO 3 + 2HNO 8 -f n (H,O) .

The essential features of this reaction may be summarized
as follows :

5PbO+2As 2 O 6 -f-H 2 Q=rPb 6 H 2 (AsO 4 ) 4 .

One part Pb 5 H 2 (AsO 4 ) 4 requires .70 part PbO and .30
part As 2 O 5 . A proper excess of lead oxide may be obtained
by increasing the quantity mentioned to .7914, which will
insure the complete precipitation of the arsenic.

Let it be required to prepare 1 pound of arsenate of lead
from samples of lead nitrate (X) and sodium arsenate (Y),
containing respectively 66 per cent. PbO and 40 per cent.

As A :

7914

X=: = 1 .1990 pounds lead nitrate.
.66

.3000

1 - - . i oOO pound arsenate of soda.
.40

Should the arseuate of soda contain 7 per cent, chlorine,
as in the preceding case, the additional amount of lead
nitrate (Z) required may be determined as follows : -

.7500X -07 X 3. 1408

Z = = . 2498 pound lead nitrate.

.66

Adding the values of X and Z, we find that 1.4488 pounds
lead nitrate and .75 pound arsenate of soda are required for
the preparation of 1 pound arsenate of lead. In avoirdupois
terms the relative weights stand as follows : 1 pound 2f
ounces nitrate of lead and 12 ounces arseuate of soda.

66 THE GYPSY MOTH APPENDIX.

Freshly prepared arsenate of lead consists of very finely
divided particles, slightly aggregated into a flocculent, curdy
white precipitate, having a specific gravity of about 1.00668,
and remaining in suspension for a remarkably long time.
The flocculent character of the precipitate facilitates its uni-
form application to the foliage, and when applied as a fine
spray it soon dries to a tenacious and permanent film. In
drying in mass this salt becomes compact and increases in
specific gravity. Analyses of two air-dried samples of ar-
senate of lead, prepared respectively from the acetate and
nitrate of lead, gave the following results :

TaUc No. 5.

CONSTITUENTS.

Sample No. 1.

Sample No. 2.

Water

Per Cent.

2.37

Per Cent.

5.11

Lead oxide, PbO,

73.10

69.85

Arsenic pentoxide, As.,O 5 , ....

21.80

24.92

Chlorine,

2.40

Trace.

Other acidulous radicals, ....

Trace.

Trace.

99.67

99.88

In the preceding table sample No. 1 was prepared from
"white granulated acetate of lead" and "50 per cent,
arsenate of soda ; " No. 2 was prepared from commercial lead
nitrate and " 65 per cent, arsenate of soda."

Where arsenate of lead is to be made on a large scale,
after determining the relative amounts of the salts to be
used it is advisable to test the formula by preparing a trial
quantity, and examining the supernatant liquid for soluble
lead and arsenic. For this purpose it is necessary to filter
a portion of the supernatant liquid. If an excess of lead
is present, by adding a few drops of potassium neutral or
bi-chromate solution a beautiful chrome yellow precipitate is
formed. A simple test for soluble arsenic acid may be made
by adding to a portion of the filtered solution a few drops

ARSENATE OF LEAD. 67

of lead acetate solution. A white precipitate indicates the
presence of soluble arsenic. From the injury to foliage pro-
duced by soluble arsenic in spraying mixtures, it is of prime
importance that the liquid should show the presence of an
excess of lead. When the nitrate of lead is used, the reaction
may sometimes show an excess of lead before the arsenic is
fully precipitated. In such cases, if the test for arsenic be
made, a decided reaction will reveal its presence, and it
becomes necessary to add a sufficient quantity of lead nitrate
to complete the reaction.

The gypsy moth committee use annually several tons of
arsenate of lead, preparing it, previous to 1897, according to
the formula originally given by Mr. Moulton, " sodic arse-
niate, 29.93 per cent. ; plumbic acetate, 70.07 per cent."
(Report of the Massachusetts State Board of Agriculture,
1893, p. 282.) Careful investigations have shown that there
is a difference in the chemical composition of these com-
mercial salts that cannot be ignored, and that single arsenic
and lead salts cannot be taken as types to fix the relative
proportions. These salts were mixed together, weighed out
in suitable quantities and placed in bags. Previous to being
added to the contents of the spraying tank, this mixture was
boiled in a kettle until the reaction between the salts was
complete. While results obtained from arseuate of lead
prepared in this manner are far superior to those obtained
by the use of Paris green, several objectionable features
developed, the principal one being an incomplete reaction
between the mixed salts stored in bags. By this process the
particles of arsenate of soda became coated with a thin crust
of arsenate of lead, and when sprayed upon the foliage broke
down, liberating soluble arsenic and injuring the leaves.
Arsenate of lead mixture prepared by grinding together the
commercial salts is also of variable composition, and gives
very uneven results. Some samples contain a great excess
of lead, while in others the arsenate of soda predominates.
Because of the incomplete reaction previously mentioned and
the uneven composition of the mixture, the arsenate of lead
thus obtained often possesses mechanical properties that
hinder its application to the foliage.

The best results in the preparation of arsenate of lead have

68 THE GYPSY MOTH APPENDIX.

been obtained by the method adopted during the season of
1897. The amounts of lead oxide and arsenic pentoxide in
the commercial salts having been determined the necessary
quantities of acetate of lead and arsenate of soda were lixed.
The work of weighing the salts was carried on rapidly by the
aid of ballasts, on balance scales. The acetate of lead was
placed in a strong paper bag which was sufficiently large to
hold the smaller bag of arsenate of soda, and the whole made
into a single package and tied with stout twine. A printed
label giving directions for the preparation of arsenate of lead
was attached to each package. When needed for spraying
the salts were dissolved separately by suspending each in a
small basket in a wooden* tub or keg of water. When the
solutions thus obtained are poured into the spraying tank
partially filled with water, arsenate of lead is thrown down
as a fine white precipitate. Acetate of lead dissolves in water
at about the rate of 1 pound to 1 gallon ; arsenate of soda dis-
solves readily at the rate of 1 pound to 3 quarts of water.
Both these salts dissolve easily in smaller quantities of hot
water, and where the latter is available it should be used in
preference to cold water. In either case great care must be
taken to avoid spilling the solutions before precipitation.

It should be recognized that the arseuate of lead commonly
sold in the market is a mixture and not a compound, and in
reality contains but about 50 per cent, of actual arsenate of
lead. In making recommendations concerning the use of this
insecticide, care must be taken to indicate whether the arsen-
ate of lead or arsenate of lead mixture is to be used. Table
No. 6 o-ives the amounts of ' white granulated acetate lead"

O

and " 65 per cent, arsenate soda" necessary to make known
quantities of arsenate of lead. In this case the acetate of lead
contains 60 per cent. PbO, and the arseuate of soda 45 per
cent. As L ,O 5 and 3 per cent, chlorine.

* Metallic pails should never be used.

AESENATE OF LEAD.

69

Table No. 6.

Arsenate of Lead.

Acetate of Lead
Required.

Arsenate of Soda
Required.

Arsenate of Lead
Mixture.

Ibs. oz.
1

Ibs.

OZ.

If

Ibs. oz.

Ibs.

oz.

2

3

-

4

Il 7 o

-

5a 7 o

5

-

6f

21

-

1

8

-

101

f

-

16*

1

1

5

Qi
5

1

144

3

3

15

1 Hi

5

10J

5

6

9

1 13i

8

6*

10

13

2

5 10^

8

12|

Table No. 7 gives the amounts of an average nitrate of
lead and the same grade (65 per cent.) of arsenate of soda
necessary to make known amounts of arsenate of lead. In
this case the nitrate of lead contains 66.5 per cent. PbO
and the arsenate of soda 45 per cent. As. 2 O 5 and 3 per cent,
chlorine. aft

Table No. 7.

Arsenate

of Lead.

Nitrate of Lead
Required.

Arsenate of Soda
Required.

Arsenate of Lead
Mixture.

Ibs.

oz.

Ibs.

oz.

Ibs.

oz.

Ibs.

oz.

-

1

-

1J

-

f

-

2

-

3

-

4

-

2

-

G

-

5

-

l

-

3|

-

10+

-

8

-

101

-

oj

-

154+

1

-

1

44

-

lOf

1

15+

3

-

3

134

9

-

5

134

5

-

6

64

3

51

9

HI

10

-

12

13

6

lOf

19

n

70 THE GYPSY MOTH APPENDIX.

EXPERIMENTS WITH INSECTICIDES.

A. H KIRKLAND, A. F BURGESS.

The dependence that necessarily must be placed upon
spraying with insecticides as a means of controlling the
gypsy moth in park lands and other places where more
heroic measures cannot be employed has led the committee
to encourage extensive investigations, under the direction of
the entomologist, of insecticides both new and old, these ex-
periments having for their object the discovery of poisons
that may be used effectively against the gypsy moth, as well
as the cheapening of the ones already in use. The discov-
ery by F. C. Moulton in 1803 of the iusecticidal value of
arsenate of lead, and the reduction of the cost of this poison
in 1897 to the extent of over one hundred dollars per ton
through joint investigations by the chemist and entomolo-
gists, are among the practical results of this work.

In the course of these experiments a mass of facts has
accumulated which it now seems desirable to place on record.
While the field of our investigations has been a limited one,
the application of the results to other insects gives the mat-
ter a wider significance. In considering the value of the
insecticides here discussed in relation to insects other than
the gypsy moth, the remarkable resistance to arsenical
poison shown by this insect should be taken into consid-
eration.

It will be noticed that the experiments in part cover the
caterpillar seasons of two years. In such cases the work of
1897 has been a continuation, on a larger scale, of that of
1896. In the indoor experiments the larvae were confined in
suitable cages and supplied daily with freshly poisoned food.
In the experiments out of doors the insects were confined in
large cloth bags upon branches previously sprayed with the

INSECTICIDES.

71

insecticide. The larvae used in the earlier experiments were
obtained by the artificial incubation of the eggs.

For the sake of brevity the results of the experiments are
presented in tabular form. The heading of each table states
the age of the larvae used, the poisons and amounts of each
to 150 gallons of water. The figures indicate the total num-
ber of larva? found dead on successive days. In each experi-
ment ten larvse were used. The check experiments afford
data concerning the normal death-rate of larva? feeding on
unpoisoned food.

PARIS GREEN v. WHITE ARSENIC.

Indoor Experiments, commenced Feb. 8, 1897. Larvae, in First

Stage.

o

kO

c"

Q>

o
o

c
v

to

cT

g

c"

8

rH

NO. OF DATS.

I*

Od

^ 1

"a

0)

S

rH
'3

s .

tjco

'3

5 S

^ i
"c

Id

cToo

'3

O
fe

<o

. """'

o

" i

an

'i^

fc.

't- '

ffi

1"

a

"i

to

0)

^

*"

EH

<1

CM

<J

<3

t

3

5

1

-

-

2

-

-

2

1

1

i

5

-

2, ....

i

3

6

1

l

2

2

1

3

8

-

3

2

5

7

O

3

5

4

2

10

10

_

4

3

6

8

7

6

9

5

9

4

5, ....

7

8

8

7

9

9

5

9

-

-

5

6

10

10

10

10

10

10

10

10

-

-

7

Duplicate Experiment, commenced March 26, 1897.

a

o

g

I

g

1

g

a"

V

v

d

I.

IM

NO. OF DATS.

*s

C8*" 1

"3

Ss

"a
a
m

-s

OD

a

V

at

|f

"3

S

<3

CH

<

PH

<

CH

<J

1

2

2

6

2, ....

6

6

8

7

6

2

4

9

3, ....

10

7

9

8

7

8

6

9

4

-

10

10

10

9

10

6

10

5

-

-

-

-

10

-

8

-

_

_

m

9

7

-

-

-

-

-

-

10

-

8

_

_

_

9, ....

10

-

-

-

-

-

-

-

-

72

THE GYPSY MOTH APPENDIX.

Duplicate Experiment, etc. Concluded.

c
<o
<o

s

1 1

c
o

V

o

CHE

CKS.

I-

tToo

id

^ i

o o

NO. OF DAYS.

Oo

'3

O-o

-- l-l

a

"oo

o

00

Is

n

No. 1.

No. 2.

No. 3.

No. 4.

(5

<

fi

<

1

4

6

4

2

2

-

-

-

Hy

6

9

4

7

2

-

-

-

3

7

9

7

10

2

_

_

_

4

9

10

7

2

9

8

2

,

6

9

9

2

7

9

-

9

-

2

-

-

-

8

9

_

9

_

2

_

_

_

9

9

-

10

-

2

-

1

-

10

10

-

-

-

2

-

1

-

* One larva lost.

Indoor Experiments, commenced April

Second Stage.

1897. Larvce in

3
O

d
ua

a
o

o
>a

9"

d

lO

H

01

o

*o

NO. OF DAYS.

3d
.S

"C 1

O r- 1

"S
0)
ID

o

DD i I

*3

a
i

o =

tTw

H
O
0)

2 .

00 1 1

. i
_o -re

'5

CD

m

^

*4

H

4

O-i

<5

04

4

PH

O

1. .

4

5

5

3

6

5

2 .

5

5

5

3

1

3

8

9

3, .

6

6

5

1

4

8

10

4, *

8

8

7

6

4

6

9

5 .

8

9

8

7

5

8

10

6 .

9

9

8

9

7

8

7 ,

10

9

10

10

9

9

g

9

10

9

9

-

10

-

-

10

-

-

INSECTICIDES.

Indoor Experiments, etc. Concluded.

NO. OF DAYS.

M

a

CD

Oo

S S
J"

Arsenic,
8-150.

a
<u

5s

a 2

2"

Arsenic,
10-150.

CHECKS.

No. 1.

No. 2.

No. 3.

No. 4.

1. .

4
6
9
9
9
9
9
10

5

8
9
10

5
5
T
8
9
10

3
5
8
8
10

-

-

-

-

2. .

4,

5. .

6

7. .

8. .

9 .

Outdoor Eosperiments, commenced May 20, 1897. Larva) in

Second Stage.

a

V

o
ia

CHECKS.

a
o

o

iO

CHECKS.

Q>

v

NO. OF
DAYS.

Cd

s

_-*

'5

3)

NO. OF
DAYS.

Od
5 S

.s*

3

,_;

(N

o

FH

c^

CO

gj.

o

O

o

3^

O

o

o

C-,

<

fc

!?!

15

<

fc

!5

t5

1, . .

3

-

-

-

-

6, . .

9

7

8

6

7

2, . .

6

4

-

-

-

7, . .

9

9

8

6

7

3, . .

7

6

-

-

-

8, . .

9

9

9

9

9

4, . .

8

7

5

6

1

9, . .

10

9

9

9

10

5, . .

9

7

8

6

7

10, . .

-

10

9

9

-

74

THE GYPSY MOTH APPENDIX.

Indoor Experiments, commenced April 15, 1S97. Larvce in

Third Stage.

cT
CD

o

a"

4)

o

a
o

g

a
o

o

la

i

(

^?

Q

T*

NO. OF DAYS.

I ~ l
"5

<U

l

_
'5

V

Oo

tTco

"5

o

Oo

"a

a rH

fcH

*i

a "

CO

'** o

<D

i-M

<

X

<!

Oi

<1

CM

<3

1, ...

*

~

3

6

2, ...

3

O

c

5

5

7

3, ....

3

4

7

6

8

8

8

10

4, ....

6

6

8

8

10

10

9

_

5, . . . .

6

8

9

8

-

-

10

-

a

o, ....

8

8

10

10

.

_

_

' * .

10

8

-

_

_

.,

^

8

-

8

-

-

_

_

M

_

9

Q

10, ....

-

10

-

-

-

-

-

-

Indoor Experiments, etc. Concluded.

a

9

g

o

0)

g

CHE

CK8.*

t.

id

_ I

NO. OF DAYS.

s

'a

OS

'o

a"

"i*

No. 1.

No. 2.

No. 3.

No. 4.

PM

<

PH

1

7

5

7

5

_

_

2

8

7

9

10

-

-

_

M

3

10

10

10

4

_

1

_

3

.

5

-

-

-

-

1

-

3

1

6, ....

i

7

i

9, ....

-

-

-

-

-

10

* Discontinued at the end of one week, as all the living larvae had molted.

INSECTICIDES.

75

Outdoor Experiments,* commenced May 28, 1897. Larvae in

Third Stage.

c

s

CHECKS.

o

CHECKS.

^7

a

.7

NO. OF

60'

.~ ^

NO. OF

^ o

~

a

B

DAYS.

a

a

0)

^

ci

CO

DAYS.

.2"

a

V

I-H

c!

CO

'

d

d

c

t* .

JO

d

d

(2

fc

fe

<3

fc

fc

!z;

1,

-

-

-

-

-

12, . .

4

6

3

-

-

2,

-

1

-

-

-

13, . .

4

6

3

-

-

3, . .

-

2

1

-

-

14, . .

4

6

4

-

-

4, . .

i

2

1

-

-

15, . .

4

6

4

-

-

5, . .

2

4

1

-

/-

16, . .

4

6

6

-

4

6, . .

4

5

1

-

-

17, . .

4

6

7

2

4

7, . .

4

5

1

-

-

18, . .

4

6

7

2

4

8, . .

4

5

1

-

-

19, . .

4

6

7

4

6

9, .

4

5

1

-

-

20, .

4

6

7

4

7

10, .

4

6

3

-

-

21, . .

4

6

7

4

7

11, . .

4

6

3

-

-

* Discontinued at the end of twenty-one days.

Indoor Experiments, commenced April 26, 1897. Larvce in

Fourth Stage.

NO. OF DAYS.

t

a

9

aj

Oo
!3

"SS

PH

o

lO

f^
1

CJ ^ H

'a
a>

QD

1-1

<

a

0)

<u

fc.

?

IB 2

'ic,

t.

Arsenic,
2-150.

n

1
Oo
S S

3d

Oi

Arsenic,
3-150.

o"

V

2

*>g

=7

I" 5

Arsenic,
6-150.

1 ,

2

4

1

4

6

5

9

2. .

4

2

5

2

4

9

8

9

3. .

7

4

6

2

6

9

9 1

9

4. .

7

6

7

5

7

9

9

10

5. .

10

8

8

10

10

10

10

6. .

10

8

_

.

7. .

8

.

8. .

9

.

.

m

9

10

.

.

m

THE GYPSY MOTH APPENDIX.

Indoor Experiments, etc. Concluded.

S3

o

8

o

.7

a
o

I

CHI

CKS.

NO. OF DAYS.

Oo
"7

3

o

| S

'3
1

No.l.

No. 2.

No. 3.

No. 4.

1

5

7

3

2,

7

q

3, .

8

a

A

4

9

g

Q

5, .

9

9

q

1

6, .

10

10

I A

1

7

g

W

2

8, .

10

_

2

9. .

2

2

Outdoor Experiments, commenced June 1, 1S97. Larvce in

Fourth Stage.

a

<D

o
*n

CHECKS.

n"

o

CHECKS.

NO. OF

Oo

. i

l-H

NO. OF

Oo

*rH

DAYS.

a

i

^

n

DAYS.

s

a

f-H

;

n

5 1 " 1

B

3

o

o

*

1

** rH

|

o

i

1,

1

-

-

-

-

12, . .

1

4

_

_

i

2, . .

1

-

-

-

-

13, .

1

4

-

-

i

3, . .

1

1

-

-

-

14, . .

2

4

-

-

i

4, . .

1

1

-

-

-

15, . .

2

4

-

-

2

5, . .

1

3

-

-

-

16, . .

2

7

-

-

2

6, . .

1

3

-

-

-

17, . .

2

9

-

-

2

7, . .

1

3

-

-

-

18, .

2

9

-

-

2

8, . .

1

3

-

-

-

19, . .

3

10

-

-

2

e, . .

1

3

-

-

-

20, . .

3

-

2

-

2

10, . .

1

4

-

-

1

21, . .

4*

-

2 4

4

11, . .

1

4

-

-

1

1 ~"~~ ^ ^ ^ ^ ^^^____^^_^^_

* Discontinued.

INSECTICIDES.

77

Outdoor Experiments, commenced June 11, 1897. --Larvw in

Fifth Stage.

a"
<a

o

CHECKS.

a
o

o

IQ

CHECKS.

a

NO. OF

u

O o

, i

NO. OF

kl

1

DAYS.

2 12

|

1-1

N

eo

DAYS.

2-2

'3

a>

~

?;

eg

S"

o

6

c! *"*

id

6

3

Q

^

&3

to

fc

&

^n

to

to

1, . .

-

-

-

-

-

12, .

6

b

3

1

-

2, . .

-

-

-

-

-

13, . .

7

6

3

1

-

3, . .

-

1

-

-

-

14, . .

7

7

5

2

-

4, . .

-

1

-

-

-

15, .

7

7

6

4

-

5, .

-

1

-

-

-

16, . .

7

j

7

4

-

6, . .

-

1

-

-

-

17, . .

9

7

7

4

-

7, . .

3

1

-

-

-

IS, . .

9

7

7

6

-

8, . .

3

1

2

-

9

19, . .

10

8

_*

_*

-

9, . .

3

1

2

-

10

20, . .

-

8

-

-

-

10, . .

3

2

2

-

-

21, . .

-

9*

-

-

-

11, . .

5

5

3

1

Discontinued.

Outdoor Experiments, commenced June 26, 1897. -- Larva' in

Sixth Stage.

[NOTE. Superior figures, in all cases, indicate the number of larvae pupating on the

corresponding days.]

a
u

o

CHECKS.

O

s

CHECKS.

.T

b

NO. OF

5d

.2 *"*

NO. OF

Oo

t

DAYS.

-s

a

V

H

N

CO

DAYS.

* '

-

X

T*

*i

".

a 1 " 1
OLI

5

1

to

tri

<J

6

to

to

1, . .

-

-

-

-

-

12, . .

41

-

-

3 =

32

2,

-

-

-

-

-

1G, . .

5

-

-

4

3 =

3, .

-

-

-

-

-

14. .

5

-

-

4

3

4, . .

1

2

-

-

-

15, .

5

-

-

4

3

5, . .

1

3

-

-

-

16, .

6

-

1 i

4

3

6, . .

1

6

-

-

-

17. . .

-

-

-

4-

3

7, . .

1

10

-

-

-

18, .

w
i

-

-

4

4

8, . .

1

-

_ i

3

1'

19, .

7

-

-

4

-

9, . .

o

-

-

3

1

20, . .

7

-

-

4

-

10, .

2

-

_2

3

1'

21, . .

8

-

-

4 =

-

11, . .

3

-

_ 5

3 1

1

78 THE GYPSY MOTH APPENDIX.

By the direction of Professor Fernald, the preceding ex-
periments were performed in order to determine the relative
iusecticidal effects of Paris green and arsenic on the gypsy
moth. While arsenic seems slightly superior to Paris green
so far as killing effects are concerned, its high specific gravity
renders it difficult of suspension in water, and hence it can-
not be applied evenly to the foliage. We have long since
abandoned the use of Paris green in our spraying operations,
and neither this poison nor arsenic can compete with arsenate
of lead as a means for destroying the gypsy moth. The
high death rate of the larvte in the check experiments is a
probable consequence of the remarkably wet season of 1897.

SCHEELE'S GREEN.
Field Experiment, June 22, 1897.

Twenty square rods of badly infested oak timber and
brush land were thoroughly sprayed with Scheele's green,
at the rate of 5 pounds to 150 gallons of water.

July 1. About 10 per cent, of the larvse are dead. Foliage slightly

burned.

July 5 ISTo more larvre dead. Foliage badly burned
July 11. Trees stripped by the larwe, except where the foliage has

been killed by the poison

In the above experiment the object was to destroy the
caterpillars, regardless of the effect upon the foliage.

INSECTICIDES.

79

LEAD ARSENITE v. LEAD ARSENATE.

Indoor Experiments, commenced June 13, 1896. Larvae, in Fifth

Stage.

NO. OF DAYS.

Lead
Arsenite,
2-150.

Lead
Arsenate,
2-150.

Lead
Areenite,
5-150.

Lead
Arsennte,
5-150.

Lead
Arsenite,
10-150.

Lead
Arsenate,
10-150.

1

9

3

4,
5

-

-

-

-

2
2

1
3

6.

1

2

4

7

2

1

2

5

3

9

1

2

5

9

2

2

3

3

9

10

2

2

4

3

9

11,

2

2

5

3

12

3

9

6

3

9

13

4

9

8

4

9

14.

2

7

2

8

4

9

15.

2

2

8

4

9

16.

2

8

9

9

4

10

17

2

8

2

10

4

18,

2

8

9

4

19

20.

2
2

8
9

2

9

-

41
4

-

21.

2

10

2

4

22,

2

2

4

23

2*

2

4

24,

2*

5

_

5

_

26

7*

.

* Discontinued.

80

THE GYPSY MOTH APPENDIX.

Outdoor Experiments,* commenced June

/Sixth /Stage.

1896. Larvw in

NO. OP DAYS.

Lead
Arsenite,
2-150.

Lead
Areenate,

2-150.

Lead
Arsenite,
5-150.

Lead
Arsenate,
5-150.

Lead
Arseuite,
10-150.

Lead
ArseiiMte,
10-150.

1,

2

3,

-

-

-

1

-

1

4,
5
6

-

-

-

1

1
1

2
2

1
2
2

7

1

2

2

Oj

9,

-

-

-

1

1

2
2

4

4

10

2

1

2

6

11

12.

2
3

-

-

1
1

2
2

6

6

13,

3

_i

2

2

6

3t

_f

2

2 i

2

7

15

2t

2t

2

16,

2

7

17

2

7

18,

2

7

19.

3

7

20.

3

8

21.

4

8

22

4

g

23,

4

8

24.

4

8 '

25.

4

9

26,
27
28,

-

-

-

4
7
S 2

No burning of foliage appeared in these experiments.

f Discontinued.

These experiments with chemically pure arsenite of lead v.
arsenate of lead mixture (containing in reality only about 50
per cent, chemically pure arsenate of lead) show the relative
superiority of the latter. The specific gravity of the arsenite
of lead is much greater than that of the arsenate, and for
this reason it cannot be so evenly applied to the foliage.

INSECTICIDES.

BARIUM ARSENATE.*

Outdoor Experiments, commenced June 1, 1896. Larvw in

Fourth Stage.

2

0-

3

aT

3

oT

C3

a

a

a

a

'a

&

c

a

a

a

a

o

o

0)

m

CO

CO

CD

CO

NO. OF

i

45

^

<5

^

t*

DAYS.

o

~ >Q

N

g

go"
= S

M

II

J4

||

^

' "-

M

"C *

4)

'^

1)

i- '

o

*n '

CD

o>

"0

01

C3

S

pa

PQ

O

a

PQ

8

1,

3, . .

1

-

-

-

i

-

1

-

1

_

_

_

4, . .

1

-

-

-

i

-

1

-

1

-

-

-

5, . .

2

-

-

-

6

-

3

-

2

-

5

-

6, . .

2

-

-

-

6

-

3

-

2

-

5

-

7, . .

2

-

-

-

6

-

3

-

2

-

5

-

8,

2

-

-

-

6

-

3

-

2

-

5

-

9, . .

2

-

-

-

6

-

3

-

2

-

5

-

10,

2

-

-

-

6

-

3

-

2

-

5

-

11, . .

3

1

2

-

8

-

5

-

5

-

7

-

12, . .

3

1

2

1

8

-

5

-

5

-

7

-

13,

3

1

2

1

8

-

5

-

5

-

10

-

14, . .

3

1

2

1

8

-

5

-

5

-

-

-

15, . .

3

1

2

1

8

-

5

-

5

-

-

-

16, . .

3

1

5

1

8

-

5

-

5

-

-

-

17, . .

3t

It

5f

It

10

-t

10

-t

10

-t

-

-t

18, . .

-

-

-

-

-

-

-

-

-

-

-

-

* Foliage uninjured.

f Discantinued.

82

THE GYPSY MOTH APPENDIX.

Outdoor Experiments. Larvce in Sixth Stage.

NO. OF DATS.

JUNE 22, 1896.

JUNE 2,

1896.

Barium
Arsenate,
12-150.*

Barium
Arsenate,
15-150.*

Barium
Arsenate,
20-150 f

Barium
Arcenate,
40-150.'

1

1
1
2
2
2
2
6
6
6
6
8
10

1
6
6
10

1
1
4

7
7
10

6
6
10

2.

3,

4,

5,

6.

7

8,

9.

10

11

12.

13

14

15,

16.

Foliage slightly burned.

t Foliage badly burned.

BARIUM ARSENATE.
Field Experiments.

Ten pounds to 150 gallons; glucose, 1 gallon to 150; 50
square rods red oak and white oak brush ; larvae in second
and third stages. Echo Street, Maiden.

Sprayed May 24, 1897 :
May 26. No results.
May 28. No results.
May 29. No results.
June 3. Few larvse dead ; foliage burned

Discontinued.

Ten pounds to 150 gallons ; glucose, 1 gallon to 150 ; 30
square rods white oak and red oak brush ; larvae in second
and third stages. Valley Street. Medford.

INSECTICIDES. 83

Sprayed May 24, 1897 :
May 26. No results.
May 28. So results.
May 29. No results.

June 3. Few larvae dead ; foliage burned ; tender foliage badly
burned. Discontinued

The barium arsenate used in the two preceding experi-
ments had stood in the " mother liquor" all winter, and had
developed a considerable amount of soluble arsenic. In the
following experiment the barium arsenate was freshly pre-
pared :

Ten pounds to 150 gallons ; glucose, 1 gallon to 150 ; 100
square rods oak, pine and white birch brush ; larvas in fourth
and fifth stages. Hawkes' Farm, Saugus.

Sprayed June 18-19, 1897 :-

June 24. Many larvre dead. Special Inspector Little agrees with me in
estimating that GO per cent, of the larvas have been killed
Not as many dead as where arsenate of lead, 20-150, is
used. No burning apparent ; poison does not show well
on foliage

June 29. Sprayed area in about the same condition as on June 24 ;
more larvae have died, but there are many large ones still
feeding ; bushes are being stripped ; poison disappeared ;
no burning of note.

July 3. Poison has stopped killing ; slight biiruing on tender foli-
age ; effect not as good as where arsenate of lead, 20-150,
is used. The greatest fault seems to be in the ease with
which the poison is washed from the foliage Larvce
pupating. Discontinued.

The experiments with barium arsenate in 1896 gave so
good results that we were hopeful that this insecticide would
prove superior to lead arsenate. Its killing effects on larvas
in confinement are certainly superior to those of arsenate of
lead. In the field spraying operations it was found that the
poison did not adhere to the foliage for a sufficiently long
time to kill the larvae. With the lessening of the cost of
arsenate of lead we have now effected, barium arsenate can-
not compete with it.

84

THE GYPSY MOTH APPENDIX.

LEAD PHENOLATE.*

Outdoor Experiments, commenced July 1, 1897. Larvae,

Fifth Stage.

NO. OF
DAYS.

Lead
Phenolate,
1-150.

Lead
Phenolate,
2-150.

Lead
Phenolate,
3-150.

Lead
Phenolate,
5-150.

Lead
Phenolate,
8-150.

Lead
Phenolate,
10-150.

1, ...

-

-

-

-

-

-

2, ...

-

-

-

-

-

-

3, ...

-

-

-

-

-

-

4, ...

_ i

-

-

-

-

_ i

5, ...

li

1

-

-

-

-

6, ...

1

5

-

-

_i

_2

7, ...

I 1

5

-

-

-

-

8, ...

2

5 1

li

_3

li

-

9, ...

2

6

1

-

1

-

10, . . .

2

6

2i

-

3

-

11, . . .

2

6

2

-

3

-

12, . . .

2

7

3 2

n

4

-

13, . . .

2

9

33

3

5

-

14, . . .

2

-

-

3

5 i

1

15, . . .

3

-

-

4

5

1

16, .

5

-

-

5

5

1

17, . . .

5 1

-

-

5

5

2

18, . . .

6

-

-

5

5

2

19, . . .

-

-

-

5

5

03

20, . . .

-

-

-

5

5

2

21, . . .

-

-

-

5

5

2 '

* Foliage uninjured.

INSECTICIDES.

85

Outdoor Experiments, commenced July _Z, 1897. Larc<v in

Sixth Staye.

NO. OF
DAYS.

Lead
Phenolate,
1-150.

Lead
Phenolate,
2-150.

Lead
Phenolate,
3-150.

Lead
Phenolate,
5-150.

Lead
Phenolate,
8-150.

Lead
Phenolate,
10-150.

1, ...

-

-

-

-

-

-

.|

-

-

-

-

-

-

3, ...

1

_ i

-

-

-

-

4, ...

1

-

-

-

_ i

-

5, ...

I 2

_ 2

_ i

_2

_i

-

6, ...

1

-

_i

2 2

-

-

7, ...

2

--

-

2

_ i

_ i

8, ...

2 i

-

_2

3 2

-

1

9, ...

3

_ 1

1

4

_ i

1

10,

3

- 2

13

-

-

1

11, . . .

3

-

1

-

1

I 2

12, . . .

4 3

-

I 2

-

li

1*

13, . . .

-

-

-

-

li

1

14, . . .

-

-

-

-

li

1

15, . . .

-

_ 1

-

-

I 2

1

16, . . .

-

-

-

-

-

li

17, . . .

-

-

-

-

-

1

18, . . .

-

-

-

-

-

1

19, . . .

-

-

-

-

-

2

20, . . .

-

1

-

-

-

-

21, . . .

-

-

-

-

-

-

PHENOLATE OF LEAD.

Field Experiment.

Grayish white salt of low specific gravity ; mixes with
difficulty in water ; particles coarse ; 10 pounds to 150 gal-
lons ; glucose, <i quarts to 150 gallons ; large apple tree
badly infested ; larvae in fifth and sixth stages. Fenwick
Street, Maiden.

Sprayed July 1, 1897 : -
July 3. No larvae dead.
July 10. No larvte dead. No burning.
July 19. Xo larva? dead. Greater part of larva? pupating.
July 21. No larva? dead. No burning Discontinued.

It would seem as though so powerful an organic poison as
phenol would have had more effect upon the larvae.

86

THE GYPSY MOTH APPENDIX.

DI-PLUMBIC ARSENATE v. TRI-PLUMBIC ARSENATE.

Outdoor Experiments, commenced July 9, 1897. Larvae in

Fifth Stage.

1
NO. OF DAYS.

Di-Plumbic
Arsenate,
5-150.

Tri-Plumbic
Arscnate,
5-150.

Di-Plumbic
Arsenate,
10-150.

Tri Plumbic
Arscnate,
10-150.

Di-Plumbic
ArseiifiU',
15-150.

Tri-Plumbic
Arsenfite,
15 150.

Di-Plumbic
Arsen.ile,

20-150.

Tri-Plumbic
Arseuate,
20-150.

1, ....

-

-

-

-

-

-

-

-

2

-

-

-

-

-

-

-

-

3
4, ....

1
2

_ 2

-

li

_ i

1

-

3 1

5

4 =

2 1

1

1

1 l

41

6

4

2 l

2

1 1

1

3-

5

41

1

4i

2

2

1

1

3i

6

4

8
9

4

4 i

2
3

3i
4

1
2

2
2

4
4

7
7

5
5

10

4

41

4

4

S

4 1

7

5

11

4

4

5

4

-

5

8

5

12, ....

4

4

6

4

-

5

8

5

13, ....
14, ....

4
5

4
4

6
6

4
4

-

5
5

8

8

5
6

J.O)

5

5

6i

5

-

5

8

6

16

6

5

6

5

-

6

8

6

17
18

-

5
5

6 1

6
6

-

-

9

6
6

19

-

5

-

6

-

-

-

6

20

-

5

-

6

' -

-

-

6

21

-

5*

-

6*

-

-

-

6*

* Discontinued.

INSECTICIDES.

87

Outdoor Experiments,* commenced July 9, 1897. Larvce in

/Sixth Stage.

SO. OF DAYS.

Di-
Plumbic
Araenate,
5-150.

Tri-
Plumbic
Arsenate,
5-150.

Di-

Plumbic
Arsenate,
10-150.

Tri-

Plumbic
Arsenate,
10-150.

* Di-

Plumbic
Arsenate,
15-150.

Tri-
Plumbic

Arsenate,
15-150.

1

o

3

4, ....

1 5

_ 2

1

2

5)

6, ....

_2

11

1

_i

I 1
1

1
41

2

3 !

7, ....

3

1

1-

4

3

Of . * .

5i

1

1

1

4't

3

5

1'

2

2

4

3i

10

11, ....

5
7

li

1

2
4 i

n

2

41
5

3i
3

12, ....

1

5

2i

4

13, ....

-

1

5

2

-

4

14

-

2

6

2

-

5 =

15

-

-

6

2 1

-

-

16

-

-

7'

2

-

-

17

-

-

-

2i

-

-

18, ...
19

-

-

-

-

-

-

20, . .
21, .

-

-

-

-

-

-

* Foliage uninjured.

t One larva lost.

88

THE GYPSY MOTH APPENDIX.

Outdoor Experiments,* etc. Concluded.

NO. OF DAYS.

Di-

Plumbic

Arsenale,

20-150.

Tri-

I'lumbic

Areenate,

20-150.

CHECKS.

No. 1.

No. 2.

No.

1,

2

3

4

5 I 1

6 1

7 1

8 . 1

9, ... .1

10,

11 5

12, 5

13 5

14 5

15 5

16 5

IT

IS

19.

20

21

_i

_2

3
3
3

3 =
4
4

4
4

4 =
4

4
4
4 1

1

3 =

32

3

3

3

3

4

* Foliage uninjured.

DI-PLUMBIC ARSENATE.

Field Experiments.

Twenty pounds to 150 gallons ; glucose, 1 gallon to 150 ;
red oak and white oak brush ; badly infested ; larva 3 in fifth

and sixth stages.

Pierce Street, Maiden.

Sprayed June 25, 1897
June 29. Killing well.

July 1. Killing- well. Stripping of foliage has stopped.
July 3. Killing well. Eighty per cent, of the larvre are dead
July 10. Killing well. Many larvre pupating
July 15. Poison nearly through killing, because of pupation of larva).

Has given excellent results ; no burning of foliage.
July 21. Few dead larvte ; no burning. Poison has killed as well or a

little better than the tri-plurnbic arsenate.

INSECTICIDES. 89

Twenty pounds to 150 gallons; glucose, 1 gallon to 150;
red oak and white oak trees of medium size, badly infested by
larvae in fifth and sixth stages. Pine Hill Path, Metropolitan
Park Reservation, Medford.

Sprayed June 26, 1897 : -

June 29. Killing well. Dead larvre plenty in path.

July 1. Killing well. Dead larvre plenty in path.

July 5. Killing well.

July 10. Killing well. Sixty per cent, of the larva) dead.

July 21. Poison still killing, although the greater part of the larva;
have transformed. No burning of foliage. The results
from the experiment are equally as good as those where
the tri -plumbic arsenate is used.

TRI-PLUMBIC ARSENATE.

Field Experiment.

Check experiment on the preceding ; 20 pounds to 150
gallons ; opposite side of path.

Sprayed June 26, 1897 : -
June 29. Killing well.

July 1. Killing well Plenty of dead larvse.
July o. Killing well. Plenty of dead larvse.
July 10. Still killing ; no burning ; about sixty per cent, of the larvse

dead.
July 21. Few dead larvte ; greater part pupated.

The di-plumbic arsenate was prepared from nitrate of lead.
So far, this insecticide seems equal if not superior to the
tri-plumbic arsenate. Extensive field experiments will be
made with the di-plumbic arsenate- during the season of
1898, should the Legislature provide means for the continua-
tion of this work.

The "di-plumbic arsenate" is composed of about two-thirds
di-plunibic arsenate and one-third tri-plumbic arsenate. The
tri-plumbic arsenate is approximately pure.

THE GYPSY MOTH APPENDIX.

DANGER FROM THE USE OF ARSENATE

OF LEAD.

A. H. KIRKLAND, M.S.

A matter of considerable importance in extensive spraying
operations with arsenic compounds is the frequent complaint
of arsenical poisoning on the part of those who apply the
poison to the foliage. In our work against the gypsy moth
such complaints are not uncommon, and, since our em-
ployees apply from two to three tons of this insecticide to
infested trees and shrubbery in a spraying season of from
four to six weeks, it has sometimes appeared that these com-
plaints might rest on a basis of fact. Cases of supposed
arsenical poisoning are of more frequent occurrence toward
the close of the spraying season ; and to get at the actual
physical condition of our men at such a time, a series of in-
vestigations was attempted late in June, 1897.

It is conceded by physicians and toxicologists that when
arsenic is taken into the system, either via the mouth, lungs
or skin, it is chiefly eliminated by means of the kidneys, and
that the presence of arsenic in the urine of a sick man is
fairly conclusive evidence of arsenical poisoning. An effort
was made, but with only partial success, to collect twenty-
five samples of urine from men who for some time had been
eno-ao-ed in spraviuo;. Two rather interesting discoveries

& O I v G O

were made at this time : first, the almost complete indiffer-
ence on the part of the men in normal health in regard to
the whole matter ; and second, the enumeration by those
who were temporarily out of health of many alarming symp-
toms which were ascribed to the effects of the poison. Only
eight samples were obtained, and these were sent to Mr.
F. J. Smith for analvsis, with the followino; results :

/ i_-

AKSENATE OF LEAD. 91

No. 1. Taken 6 A.M., June 27. Man in good health; had been en-
gaged in spraying about two weeks ; trace of arsenic found.

No. 2. Taken 8.15 A.M., June 24. Man enjoyed good health up to the
spraying season ; had been engaged in spraying three weeks
and during the last week had suffered from loss of appe-
tite, with considerable disturbance of the digestive system ;
17.6 mg. arsenic per litre were found.

No. 3. Taken 12 noon, June 24. Man in fair health, aside from an
occasional "bilious attack;" had sprayed for three weeks;
no arsenic found.

No. 4. Taken 12.30 P.M., June 24 Man in good health, but appetite
poor at times ; had worked at spraying for three weeks ; no
arsenic found.

No 5. Taken 1.30 P.M., June 24. Man in excellent health; had
sprayed for six days ; trace of arsenic found.

No. 6. Taken June 26. Man in poor health; was well until after he
had worked at spraying about two weeks ; had sprayed
nearly four weeks ; trace of arsenic found.

No. 7. Taken June 26. Man had complained of various derangements
of his digestive system ; had sprayed for " over three weeks ; "
.2 mg of arsenic per litre found.

No. 8. Taken June 1. Man in poor health ; had been engaged in ex-
perimenting with Paris green and other arsenical compounds
for about three months ; 4 mg. arsenic per litre found.

The results of these analyses show conclusively that in
some cases men engaged in spraying acquire dangerous
amounts of arsenic. That actual sickness resulting from this
work is rare, is shown by the fact that but few of our many
employees lose time from this cause. A case of this kind
investigated by the writer in 1806 proved to be one of un-
mistakable arsenical poisoning, which in this instance was
not strange, since less than one week previous to the time
the man was taken sick he was observed to be especially
careless in the use of the poison, allowing the drippings of
the spraying pole to run freely up his arms and probably over
the greater part of his body. Nowhere, perhaps, do we find
a better illustration of the contempt bred by familiarity than
in the manner in which men ens'ao'ed in spraying make use

~ ~ i . C 1

of insecticides. In the case of our employees an excuse is
found in the high state of physical vigor that characterizes
the whole force, the natural result of an active, outdoor
life.

Strangely enough, the most frequent cause for complaint

i2 THE GYPSY MOTH APPENDIX.

in the use of arsenate of lead is an entirely harmless one.
The odor of the spray when very pronounced often causes
considerable anxiety among- those engaged in spraying, and
in one or two cases has been known to produce nausea.
This odor is not produced by the arsenic or the lead, but is
the rich creosote smell remaining in the crude acetic acid
used in the manufacture of acetate of lead. This acid is one
of the resultants of the destructive distillation of wood, and
retains the smoky odor even after passing through several
chemical reactions.

It may be stated, in general terms, that w r hile an occa-
sional person may become poisoned during extensive spray-
ing operations with arsenate of lead, premonitory symptoms
appear in ample time for a change of work to be arranged ;
and since the conditions existing in the work against the

O O

gypsy moth are exceptional, the farmer or fruit grower may
use this insecticide with less fear of danger from poisoning
than is the case where Paris green or London purple is used.
In all cases proper care must be taken in handling the poison
and in preventing the exposure of the skin to the spray.

The danger to animals from feeding on grass under trees
that have been sprayed is a matter that has at times received
a large measure of popular attention in the region infested
by the gypsy moth, and at the time of spraying we have
always taken the precaution to advise all property owners of
the possible danger to their fowls and live stock. The ex-
periment detailed below is of interest in this connection.

On June 26, 1896, sufficient grass to make two large feed-
er 53

ings for a horse was cut and spread beneath a pear tree of
medium size, and the tree heavily sprayed with arsenate of
lead, at the rate of 20 pounds to 150 gallons of water. The
drippings from the tree were not sufficient to discolor the
grass to any marked degree, so the nozzle was turned on
to the grass, and the latter thoroughly drenched. By a
previous arrangement with Miiller Brothers, tannery pro-
prietors, North Cambridge, a horse had been secured for
experimental purposes. This horse weighed about 1,200
or 1,300 pounds, was perfectly sound except for a badly
sprained leg, and because of this latter defect was soon to be
slaughtered. The grass treated as described was taken to

AKSENATE OF LEAD. 93

the tannery and fed to the horse during the afternoon and

evening of June 26. On June 28 the writer found the

horse well and hearty, and in " better condition," so the
teamsters at the tannery stated, than before the grass had
been fed to him. The poison used in spraying was mixed
with cold water, and in a few days it was found that the
foliage of the pear tree was badly burned, thus proving the
presence of soluble arsenic in the mixture, and showing that
it was even more dangerous to animal life than properly
prepared arsenate of lead would have been.

LIBRARY^

94 THE GYPSY MOTH APPENDIX.

DIGESTION IX THE LARVAE OF THE

GYPSY MOTH.

A. H. KIRKLAND, F. J. SMITH.

The remarkable resistance exhibited by the larvre of the
gypsy moth toward internal poisoning has afforded a basis
for the suggestion, so frequently made, that the digestive
functions in this insect may diifer either in character or in
degree from that of insects more readily killed by arsenical
poisons. To gain a better idea of the nature of the diges-
tive process in the gypsy moth larva, a limited series of
investigations was made in the summer of 1896 by the
writers, Mr. Kirkland attending to the anatomical and physi-
ological phases of the question, and Mr. Smith conducting
the chemical analyses. It was hoped at the time these inves-
tigations were discontinued that further study of the subject
could be made during the summer of 1897, but this has been
prevented by the demands of other work. Although but a
few points are established by our studies, it now seems
advisable to publish them as a contribution to the knowledge
of digestion in insects. We may properly state here our
belief in the importance of a thorough understanding of
this subject, and that whenever it is reached many obscure
points in the behavior of different insects toward internal
poisons will be cleared up.

That the processes taking place in the alimentary canal
of the gypsy moth larva may be better understood, it may be
well to briefly consider the composition of the food consumed
and the anatomy of the digestive tract.

THE FOOD OF THE GYPSY MOTH.

In common with other Bombycid caterpillars, the larvae
of the gypsy moth are practically confined for food to leaves
of trees, shrubs or plants ; in certain rare cases this insect

DIGESTION. 95

has been known to devour bark, buds, blossoms and fruit,
but, as these are exceptions, they may be properly excluded
from consideration.

Leaves may be said to consist of a large amount of organic
matter associated with water, and a small quantity of mineral
matter. In the ash are found certain elements, such as pot-
ash, lime, phosphorus, etc., which play an important role
in plant economy ; but the substances serving as food in
leaves are organic, and consist mainly of proteids, carbohy-
drates and fat. These compounds are present in the proto-
plasm with which the cells are filled, and, w r hen consumed and
assimilated by the insect, serve as muscle builders, sources
of fat, energy and heat, repair wasted tissues and bring
about the normal growth of the insect. Undoubtedly the

*_. *

proteids are the most important food elements, and probably
serve as the source of the chitin of which the body integu-
ment is formed. The lignin, cellulose and similar substances
found in leaves are of but little value as food.

THE DIGESTIVE SYSTEM.

The internal .anatomy of the larva, pupa and imago has
been fully detailed in another place,* hence it will suffice to
state that the digestive system of the larva consists of a pair
of stout jaws, a buccal cavity, a pharynx dilating into an
anterior stomach in the forward body segments, a stomach
proper, extending through a greater part of the body cavity,
an intestine and a short dilated rectum. Discharging into
the mouth are a pair of salivary glands, while six malpighian
vessels are attached to the rectum.

THE DIGESTIVE PROCESSES.

The jaws of the larva serve to incise and comminute the
food which passes directly from the mouth into the anterior
stomach, where it is subjected to the action of an alkaline
fluid. It is of interest to note that in this stomach, some-
times greatly distended with food, there is always a large

* Kirkland, article on "Internal Anatomy;" "The Gypsy Moth," Forbush-
Fernald, 1896.

96 THE GYPSY MOTH APPENDIX.

amount of fluid present. From the anterior stomach the
food passes backward into the posterior stomach (the
stomach proper), an organ well supplied with strong an-
nular muscle fibres. In this organ the disintegration and
digestion of the food become more marked. By the action
of the stomach muscles the food is gradually forced along
until it reaches the narrow intestine, through which it passes
to the rectum, from which the refuse material is voided from
time to time.

Microscopic examinations of the contents of different
parts of the alimentary canal show that the greater part
of the food retains much of its original physical character.
The fibrous elements pass through the system practically
unchanged. The softer tissues undergo a partial disintegra-
tion, but in general the cellular structure can be recognized.

O

In the contents of the cells, however, there is a great
change ; in food removed from the anterior stomach the cell
contents showed only a partial destruction, while in samples
from near the intestine the protoplasm had nearly disap-
peared, only the chlorophyll granules remaining. From
these examinations it appears that the process of digestion in
this larva is practically one of solution or extraction : the
digestive fluids dissolve the soluble proteids, carbohydrates,
fats, salts, etc., while the insoluble parts are eventually
ejected. The stomach muscles do not perform the function
of grinding, otherwise the physical characters of the food
would be destroyed before it reached the intestine. Doubt-
less the function of these muscles is to force the stomach
contents posteriorly, and by this movement bring the food
more thoroughly in contact with the digestive fluids ; the
same is probably true of the weaker muscles of the anterior
stomach, although these muscles are equally capable of
reverse peristalsis, as shown by the ejection of a part of the
contents of this organ from the mouth of the larva when-
ever the insect is roughly handled.

According to Plateau, the products of digestion in herbiv-
orous insects consist of salts in solution, peptones, sugar
and emulsified fats. These substances pass by osmosis
through the walls of the alimentary canal and mingle with
the blood.

DIGESTION. 97

The Alkalinity of the Alimentary Canal.

At the time the article on the anatomy of the gypsy moth
was prepared it was noticed that the digestive fluids of the
larva were strongly alkaline ; but, while the fact seemed
quite suggestive, investigations of the cause of this alkalin-
ity were deferred until such a time as the assistance of a
chemist could be obtained.

For a preliminary examination several full-grown cater-
pillars were killed by exposure to fumes of chloroform, and
the alimentary canal of each carefully removed and washed.
After maceration in water the material was subjected to a
careful analysis for both organic and inorganic bases and
acids, but nothing of an organic nature that could give an
alkaline reaction to the digestive fluids could be detected.
Repeated examinations of the water extract, however, showed
the presence of appreciable amounts of phosphoric acid and
potassium, with traces of calcium and magnesium. It is
well known that the phosphates of potassium and sodium
give an alkaline reaction with litmus, and, since the presence
in the digestive fluid of comparatively large quantities of
potassium and phosphoric acid was proven^ it was apparent
that the alkalinity of this fluid is due to the presence of a
phosphate of potash.

Having thus determined qualitatively the source of the
alkalinity, it seemed desirable to make a quantitative analysis
of the digestive systems of a number of larvae, in order to
obtain an accurate idea of the amount of phosphates of potash
occurring in each insect. For this purpose the following
method was adopted : the alimentary canals of sixty-six
larvae were carefully removed, washed and macerated in water,
as in the previous analysis, and, it having been found that
the albuminous substances contained in the material seriously
interfered with filtration, resort was made to dialysis, with
good results. The macerated material was placed in a
dialyzing apparatus and suspended in a dish containing a
large quantity of freshly distilled water, the whole being
kept at a cool temperature, and the water in the dish replaced
with a fresh supply at intervals of twelve hours each for
seventy-two hours. At the end of this time the water taken

98

THE GYPSY MOTH APPENDIX.

from the dish was evaporated to a convenient volume upon a
water bath, when aliquot parts of the liquid were taken for
the determination of phosphoric acid and potash. The phos-
phoric acid was determined by the ammonium molybdate
method and the amount of potash estimated as the double
chloride of platinum, following as closely as possible the
methods of fertilizer analyses adopted in 1895 b}^ the Asso-
ciation of Official Agricultural Chemists. Briefly stated, the
results of these analyses were as follows :

Phosphoric acid found in 66 larvae, .
Potash (K. 2 O) found in 66 larvse,
The phosphoric acid as above stated,
in the form of tri-potassic phos-
phate, requires of potash,

Error,

Grams.

.036998,
.073750,

.073450

.000300

per larva,
per larva,

Milligrams.

.560
1.117

This shows conclusively that the phosphoric acid and
potash in the alimentary canal of this insect exist in the form
of tri-potassic phosphate, K 3 PO 4 .

STUDIES ON OTHER LEPIDOPTERA.

To learn how commonly phosphate of potash occurs in the
alimentary canal of Lepidoptera, a number of larva} were
dissected and the parts removed for analysis. The following
table presents the results of the analyses. Unless otherwise
stated, the data pertain to the alimentary canal of the larva
of the species mentioned.

DIGESTION.

99

Amount of
Potash.

Amount of
Phosphoric
Acid.

Sphingidce.

1. Thyreus abbotii,

Fair,

Fair.

2. Thyreus abbotii (excrement),

Small,

Trace.

3. Deilephila chama'ncrii Harr.,

Fair,

Fair.

4. Philampelus achemon Dru., ....

Fair,

Large.

5. Protoparce celeus Hbu., ....

Fair,

Large.

6. Protoparce celeus (second specimen), .

Large,

Fair.

1, Sphinx drupiferarum S. and A., .

Fair,

Fair.

8. Sphinx gordius Cram.,

Fair,

Fair.

9. Sphinx gordius (excrement),

Small,
Small,

Trace.
Fair.

11. Cressonia juglandis S. and A., .

Fair,

Fair.

Arctiidce.

12. Pyrrharctia Isabella S. and A.,

Fair,

Large.

13. Spilosoma virginica Fabr., ....

Fair,

Fair.

14. Eyphantria cunea Dm., ....
15. Ealesidota caryce Harr.,

Fair,
No test
made,

Large.
I Small.

Liparidce.

16. Orgyia leucostigma S and A.,

Fair,

Fair.

17. Porthetria dispar L. (rectum),

Fair,

Small.

18. Porthetria dispar (excrement of female), .

Fair,

Large.

19. Porthetria dispar (fertile nest), .

Fair,

Large.

20. Porthetria dispar (fertile nest), .

Large,

Large.

21. Porthetria dispar (infertile nest),

Large,

Large.

Notodontid(K.

22. Datana ministra Dm.,

Small,

Small.

23. Datana ministra (newly hatched larvae,
whole insect),

Trace,

Trace.

24. Datana integerrima G. and R., .

Large,

Large.

8aturniid(R.

25. Attacus cccropia L. (eggs), ....

Large,

Large.

26. Hyperchiria io Fabr.,

Fair,

Fair.

Ceratocamp idee.

27. Anisota senatoria S. and A., ....

Fair,

Fair.

100 THE GYPSY MOTH APPENDIX.

The results of these analyses show that phosphate of pot-
ash, although varying in amount, is a constant ingredient of
the digestive fluids of leaf-eating Lepidoptera, and this fact
gives additional evidence of the importance of the substance.
We would call particular attention to the fact that but little
of this compound was found in the excrement examined
(Nos. 2, 9). This shows that the phosphate of potash is
retained in the system, since the analyses of the alimentary
canals of the corresponding insects (Nos. 1, 8) revealed a
fair amount of the substance.

THE FUNCTION or PHOSPHATE OF POTASH IN LEPIDOPTERA.

In the larvae examined, phosphate of potash was always
found associated with albuminoids. This coincidence, which
is also common in plants, seems to show that in living or-
ganisms there is an intimate relationship between these sub-
stances. Schumacher states that if alkaline phosphates " are
mixed with a solution of albumen, or if a solution of them
is permitted to diffuse against one of albumen, a much
greater amount of the latter will pass through the membrane
than would otherwise be the case."

In the fluid obtained as a result of the dialysis of the
digestive systems of dispar larvee a small amount of albumen
was found associated with the phosphate of potash. This
albumen would not coagulate upon the application of heat,
but was precipitated by the addition of alcohol.

From the physiological stand-point the natural inference
is that the phosphate of potash aids in the assimilation of
albuminoids. The facts in the case may be briefly stated as
follows :

Albuminous substances form an important part of the in-
sect's food. The process of assimilation in dispar is one
of osmosis. Albuminous substances do not readily pass
through the stomach walls, but phosphate of potash aids
them in their diffusion. Since this compound is present in
such large quantities, it seems evident that its function is, as
stated, to aid in the osmosis of albuminoids through the
walls of the alimentary canal into the blood.

" Physik der Pflanze, " 1867, p. 129.

DIGESTION. 101

We incline to the belief that this compound plays a most
important role in the economy of the insect, in connection
with the digestive process and also in the changes taking
place in the pupal state. It seems probable that the phos-
phate of potash bears a somewhat intimate relation to the
development of the reproductive system, since eggs of both
fertilized and unfertilized female moths contain large quanti-
ties of this compound (Nos. 19, 20, 21). It also occurs in
the thick fluid ejected by newly emerged imagoes (No. 18).

Relation to Insecticides.

In connection with the discovery of the source of the alka-
linity of the digestive fluids of gypsy moth larvae, two lines
of insecticide experiments suggest themselves :

1. To introduce into the digestive system of the larva
some substance that shall be inert in neutral or weak acid
media, and which shall react with phosphate of potash, liber-
ating an effective poison.

2. To obtain a substance that, when taken into the di-
sestive system of the insect, shall precipitate the phosphoric
acid, thus destroying its function and preventing the assimi-
lation of albuminous food materials.

102 THE GYPSY MOTH APPENDIX.

NOTES ON PREDACEOUS BEETLES, 1897.

A. F. BURGESS, M.S.

During the season of 1897, predaceous beetles, especially
those belonging to the genus Calosoma, have been abundant
in many localities infested by the gypsy inoth, in marked
contrast to the condition last year, when considerable diffi-
culty was experienced in obtaining sufficient examples of
Calosoma frigidum Kirby for making studies on its life
history. During the past summer the study of this group
of beneficial insects has been continued, several new facts
concerning their habits ascertained, and the statements made
by the writer in the last annual report of the committee have
received additional verification.

The climbing habits of the genus have been noticed this
year more than ever before, and the killing of caterpillars by
these beetles, even in the tallest trees, has been repeatedly
witnessed. In a colony of the gypsy moth in Saugus, June
25, 1897, C. frigidum was observed to climb nearly to the
top of a small oak tree and feed upon the caterpillars. When
in the top of the trees or at the ends of the limbs, if the tree
is suddenly shaken by the wind the beetles often drop to the
ground, and in a piece of woodland where they are abundant
they are often heard striking upon the leaves, having fallen
or dropped from the trees.

Mr. W. W. Stevens, an inspector who worked in the
Saugus colonies, where beetles of this genus were common,
informs me that on two occasions he has seen specimens of
C. frigidum fly, or rather " scale," to the ground from a tree
after the manner of a flying squirrel. I have occasionally
noticed that the beetles vibrate their wings in confinement,
but have flung them into the air repeatedly without seeing
them make the slightest effort to fly. Mr. Stevens is of

PREDACEOUS BEETLES. 103

the opinion, however, that they would not fly upward, but
simply extend their wings to lessen the velocity of the fall.

Calosoma scrutator (Fab.) has been found to be fully a,s
active, particularly as regards climbing, as frigidum, and,
on account of its greater size and strength, is a more for-
midable enemy to caterpillar life. The amount of good done
does not depend entirely on the number of larvae which the
beetles actually eat, as when food is plenty they kill or
mutilate a great many which they make no pretence of eat-
ing, as is shown by the following statement. Mr. Harry
Vinton, while working in a colony of the gypsy moth in
Saugus, during June, 1897, saw a C.frigidum kill or wound
seven of the caterpillars on a tree trunk and then disappear
among the brush. All the larvte were so badly disabled that
they could not recover.

The representatives of this genus are found principally in
the spring and early summer, and after laying their eggs
probably remain in the ground. This has been found to be
the case with the beetles kept in confinement in cages. After
midsummer the food supply is usually less plentiful, and
these beetles probably do not feed on vegetable matter dur-
ing the latter part of the season, as do some other Carabids.
Harpalus caliginosus (Fab.), for example, was taken Sep-
tember 23, feeding on the flower-heads of the ragweed (Am-
brosia artemisioefolia), one of our most common garden
weeds.* Professor Forbes, in his studv of the food of

*/

Carabidse, found, from dissecting three C. scrutator and nine
C. caUdum, that only food of animal origin was present in
the stomachs. He also emphasizes the fact that the mouth
parts of this genus are adapted for animal rather than vege-
table feeding.f

*The Calosomas, aside from being able to hibernate as ima-
goes, can also live an almost incredible length of time without
taking food. The following notes may be of interest in this
connection. A single female of Calosoma ivillcoxi~Lec., kept
in confinement, ate nothing from June 30 to August 18 ;

7 ~ o

several specimens of C. frigidum, confined in a breeding

* This observation corroborates those of Wm. Trelease ("American Entomolo-
gist," 1880, p. 251) and Wm. A. Buckhout (ibid., p. 277).
t Bulletin Illinois State Laboratory of Natural History, Nos. 3 and 6, 1883.

104 THE GYPSY MOTH APPENDIX.

cage, received no food from July 21 to September 1 ; and
specimens of C. scrutator have been kept two weeks without
food. In all these cases the beetles survived, and seemed to
suffer no serious inconvenience. They were, however, a
little more sluggish in movement, and remained in the ground

(_, ^j ' <_.

more than was the case earlier in the season, when food was
plentiful. One of the principal reasons for allowing the
beetles to be without food was the scarcity of caterpillars
after midsummer. Substitutes for larvre, such as snails, beef,
veal, kidney and grasshoppers, were tried, with very poor
results. When snails were used as food for the beetle larvas,
their legs soon became covered with slime, and death followed.

CALOSOMA FRIGIDUM Kirby.

Sept. 24, 1896, two males and three females of this species
were placed in a wire cage near the iusectary. The cage
consisted simply of a cylinder of wire mosquito netting sunk
nearly to the level of the ground, the top being covered with
a cloth which was held in place by an elastic band. The
records of these three females are given here in full. They
were captured June 4, 19 and 26, 1896, and each of the first
two were immediately placed in separate jars with a male
beetle. The first laid seventeen eggs June 5, but deposited
no more during the season, although the male was kept in
the jar and placed in the cage outdoors at the same time with
the female. The second female laid two eggs July 16 and
one more on the 18th, the male dying July 22. The third
female had no male companion until August 7, and laid
no eggs whatever.

On examining the outdoor cage, May 10, 1897, a live
beetle was found about four inches below the surface. The
cage was covered, but before another examination was made
the netting became partly detached and three of the beetles
undoubtedly escaped, as only two females could be found in
the ground May 17. They were quite active, and had par-
tially eaten a full-grown white grub (Lachnosterna sp. ?)
which was in the cage. No remains of the other beetles

O

could be found, although the ground was examined to the
depth of nearly a foot. This shows conclusively that the
beetles hibernate as adults.

PREDACEOUS BEETLES. 105

The two female beetles were placed in separate breeding
jars in the insectary and supplied with food, but very little
was eaten until June 2, when males were placed in the jars.
One female began laying June 6, finished July 14, having
deposited eighty-one eggs, and died on the 24th. The other
female began laying on the same date as the former, but
finished June 25, dying July 3, having deposited one hun-
dred and fifteen eggs. The largest number laid in a single
dav was nineteen, which is the maximum noted for this

J

species. From the above it will be seen that these two
females were kept in confinement for over a year, and
that one, if not both, deposited eggs two years in suc-
cession. This naturally brings up the question of the
number of annual broods of this insect. From the fact that
the egg-laying season ranges from the first of June to the
middle of August, I am inclined to believe from present
knowledge that the greater portion of the species winter as
adults which have seldom laid eggs the previous year.

Observations in the field show that after the last part of
June the occurrence of this species is very rare. Mr. "VV.
C. Colt, a special inspector of the Board, with the aid of
two men captured thirty-one specimens of this species June
24, while at w r ork in a colony of the gypsy moth in Brook-
line, and informs me that previous to and about this time
the beetles were abundant. On the following da}' he noticed
a female laying her eggs, for which purpose she had selected
a place about half an inch below the surface of the ground.
Mr. Colt further states that from a week after this date to the
end of the season not a single beetle was observed. This
species has also been found during the past year in Saugus,
Winchester, Medford and elsewhere.

Jars partly filled with earth were used for close breeding
with about the same amount of success as during the pre-
vious season, the results, however, substantiating the facts
which were observed last year. Much of the material con-
fined in jars was attacked by mites, while the outdoor
experiments were rendered almost useless by the attacks of
ants.

In order to test the practicability of rearing the beetles out
of doors, a suitable spot was selected beside two small oak

106 THE GYPSY MOTH APPENDIX.

trees, and a cage with a ground area of about a square yard
was built. About the middle of June ten males and a like
number of females ofrigidum were placed in the cage, with
plenty of caterpillars. Some of the beetles paired the fol-
lowing day, and on examining the ground June 28 a beetle
larva was found. Subsequent examinations, however, failed
to bring to light any larvae, and, as ants were numerous in
the cage, this doubtless accounts for the non-development of
larvae that may have hatched.

The killing of young beetle larvae by the common black
ant (Oamponofus pennsylvanicus DeG.) has been previously
noted. Several jars containing newly hatched larvae of
C. frigidum were accidentally left uncovered over night.
In the morning seven of the eleven larvae present had been
killed, and the ants were feeding on the bodies. One hun-
dred and six larvte which were placed in another outdoor
cage during the season suffered in the same manner from

C C 1

ants, and not one completed its transformations.

Some of the larvae reared in jars until nearly full grown
were placed in small cages out of doors, but they were so
badly attacked by mites * that none pupated successfully.
In one of these cages a larva of this species was attacked
by a wire-worm (Asaphes sp. ?), the integument being rup-
tured so badlv that the larva diecl.t

/

CALOSOMA SCRUTATOR (Fab.).

This beetle, known under the common names of beautiful-
bodied searcher, rummaging or green Calosoma, has for
years been recognized as one of the most useful predaceous
insects. Almost every report on injurious insects credits it
with preying upon noxious species. The following list of
some of the injurious larvse which this beetle has been
known to attack has been compiled from various sources :

Tobacco worms, Protoparce (sp. ?).
Gypsy moth, Porthetria (Uspar (pupa also).
Tent caterpillar, Clisiocampa americana.

* Through the kindness of Dr. L. 0. Howard these mites have been determined
by Mr. Nathan Banks as an immature stage of a species of Histiostoma.

t A somewhat similar occurrence has been mentioned by Riley in "Insect Life,"
vol. II., p. 299.

PREDACEOUS BEETLES. 107

Forest tent caterpillar, Clisiocampa disstria.

Army worm, Leucania unipuncta.

Cotton worm, Aletia argillacea.

Lime tree winter moth, Hybernia tiliaria.

Spring canker worm, Paleacrita vernata.

Fall canker worm, Anisopteryx pometaria.

Oak Tortricid, Cacoecia fervidana.

Rocky Mountain locust, Caloptenus spretus (nymphs) .

This shows C. scrutator to be a very general feeder, and
that it is particularly fond of our common injurious lepidop-
terous larvas. When kept in confinement at the insectary,
single beetles killed on an average about four full-grown
gypsy moth caterpillars daily. Out of doors the number
killed would be increased, as the appetite of the beetles is
greater under natural conditions than when kept in confine-
ment.

Calosoma scrutator is found in Canada and the New Eng-
land States, but is more locally than generally distributed.
It is more common in New York and the Middle States, and
occurs throughout the United States . Specimens were found
this year in infested woodland in Saugus, and through the
efforts of Mr. W. W. Stevens a number was received for
rearing purposes. The first beetles were received and placed
in breeding jars June 24. They fed readily and mated sev-
eral times, but only seven eggs were laid during the season,
six being laid by one female, June 26, and a single egg being
deposited by another female, July 1. It is probable that
this species, like the other Calosomas thus far observed, lay
the bulk of their eggs earlier in the season, and it may be
that the females had nearly finished depositing eggs before
being placed in confinement.

A part of the eggs was preserved for further study, those
remaining in the jar hatching in eight days; all the larvse
died, however, before molting. This species does not thrive
in confinement as well as either frigtdum or calidum. August
9 a coarse wire cage was constructed near the insectary, in
which were placed nine females, which went into the ground
immediately, without taking food. This cage will be exam-
ined in the spring, and notes on the hibernation of the
species completed.

108 THE GYPSY MOTH APPENDIX.

CALOSOMA WILLCOXI Lee.

This species was first described by Dr. Leconte in 1848.
It is smaller than any of our Calosomas previously studied,
and from its green color might be easily mistaken for a
diminutive scrutator. The middle tibia of the male, how-
ever, is straight and not hairy, while that of the male
C. scrutator is curved, and has a dense brush of hairs on the
inner surface near the tip. It occurs in Canada and the
United States and has been reported very abundant in Mary-
land, but is very rare in this vicinity. Its feeding habits are
the same as those of the other members of the genus. Kiley *
reported it feeding on nymphs of the Eocky Mountain locust,
and in Canada it has been found climbing the trees and feed-

O

ing on canker worms, f

Only one specimen has been under observation this season.
On June 9, Mr. C. E. Bailey, an agent of the Board, cap-
tured this beetle in Newton and brought it to the iusectary
in perfect condition, where it was confined in a breeding jar.
The following day nine eggs were found about an inch below
the surface of the earth ; only one hatched, the others prob-
ably being infertile. The larva was deformed and very slug-
gish in movement, taking no food whatever, and died two
days after hatching. No more eggs were laid, however, and
June 30 the beetle went into the ground, where it remained,
and ate nothing, until August 18.

The beetle was supplied with full-grown forest tent cater-
pillars ( Clisiocampa disstria) and third and fourth molt
gypsy moth larvas, and consumed on the average about one
larva per day. Female beetles, however, never eat as large
an amount of food when isolated as when confined with
males. x

Although willcoxi has never been observed feeding on the
gypsy moth in the field, from the fact that it occurs in the
infested districts and feeds on the larvae in confinement, it
may be safely enumerated as an addition to the list of natural
enemies of P. dispar.

* First Report United States Entomological Commission, 1878, p. 314.
t Harrington, Report Entomological Society, Ontario, 1893, p. 24.

PREDACEOUS BEETLES. 109

CALOSOMA CALIDUM (Fab.).

On the 23d of May a male and female were placed under
observation in a breeding jar, and were noted to pair on each
of the three succeeding days. The first eggs were laid May
31 ; the female died July 24, after having deposited eighty-
eio-ht eofo-g. The larvas hatched in about a week from the

* ' ^ * !

date of oviposition, and were isolated in jars and carefully
fed daily. A large proportion reached the third larval stage
in a health}- condition. At this time the same difficulty was
experienced as last year, viz., the dying of the lame with-
out any apparent cause.

Quite a number of the larvae pupated, however, but on
examining the jars a few days later the pupre were found to
be dead, having been attacked by mites.* A full-grown
larva of C. calidum, which was found July 4, fed a few days
and pupated in one of the breeding jars, but shared the
same fate as the others.

PTEKOSTICHUS LUCUBLANDUS (Say).
This is one of our most common around beetles, and is

O

often found under stones or running about in the grass dur-
ing the summer. While the members of this genus are con-
sidered to be predaceous on other insects, certain species
have been charged with doing some damage by feeding on
vegetation. This is probably true to some extent, but when
these insects are abundant they doubtless do considerable
good by feeding on noxious species.

A pair of lucublandus were taken in coitu under a large
rock, June 2, 1897. They were placed in a breeding jar
and fed with gypsy moth caterpillars. The smaller ones
were devoured greedily, the larger ones, as a rule, being
rejected. On July 4, however, I observed the male beetle
attack a fourth molt larva of this species. The caterpillar
was grasped just behind the head, and, after a fierce struggle,
the beetle succeeded in cutting a hole through the integu-
ment and began to feed upon the internal portions with great

* Identified by Mr. Banks as " the nymph of some Oribatid, probably of the genus
Oribata."

110 THE GYPSY MOTH APPENDIX.

avidity. In addition to gypsy moth larvae, other small
caterpillars were provided, which they ate with apparent
relish. A pupa of Orgyia leucostigma was also eaten by
the beetles. The average consumption equalled about one
small gypsy moth caterpillar daily. In killing noxious in-
sects these beetles probably will not be found as helpful
as some of the larger species of Carabidfe ; although they
take most of their food on the ground, they are sometimes
taken under burlaps, thus indicating that they may also feed
in trees.

On June 9 several eggs were found in the earth, from one-
fourth to one inch below the surface. Eggs were also laid
as follows: June 10, nine; 11, nine; 18, six; and on the
29th, three, making a total of over thirty eggs deposited.
After the last date no eggs were laid. August 19 the female
beetle escaped in some unknown way, and the observations
with the adults were discontinued. A few of the eggs
hatched, but all the larvae died before pupating.

HARPALUS CALIGINOSUS (Fab.).

This beetle has been often observed feeding on injurious
insects. Among the common ones which have been most
frequently noted in the literature are cut worms, army worms
and the Colorado potato beetle in its different stages. Pro-
fessor Riley * found that large numbers of nymphs of the
Rocky Mountain locust were consumed by this beetle, while
Dr. Howard f has noted that it feeds on the nymphs of
another destructive locust, Schistocem americana. It is a
fact, however, that the food of this beetle consists partly
of vegetable matter. I have several times observed it feed-
ing on the flower heads of Ambrosia artemisicefolict, and it
has been accused of eating wheat in the stack. Professor
Forbes J has discovered some interesting facts in regard to
the food of this species by examining the stomach contents.
Two specimens, collected in August and September, respec-
tively, were found to have eaten 35 per cent, of animal inat-

* First Report United States Entomological Commission, 1878, p. 314.

t " Insect Life," Vol. VII., p. 228.

J Bulletin Illinois State Laboratory of Natural History, No. 6, 1883, p. 45.

PREDACEOUS BEETLES. Ill

ter, while the remainder was of vegetable origin. Of the
animal matter, '20 per cent, could not be identified, 10 per
cent, consisted of insect food, caterpillars and Diptera being
represented, while the remaining 5 per cent, were mites.
The vegetable food consisted chiefly of the tissue of grasses
and a little pollen from flowers belonging to the family Com-
posite. In addition to the above, the spores of a fungus
(Helminthosporium) amounted to 3 per cent. This shows
conclusively that vegetable food is taken freely during this
time of year. The fact that the beetles eat such vegetable
matter as pollen, seeds of common weeds and spores of fungi,
should be counted in their favor rather than against them ;
and if they are able to subsist on such food during the season
when caterpillars and noxious insects are scarce, it is in-
deed a wise provision. If, however, subsequent observa-
tions and investigations show that they actually feed to any
irreat extent on wheat or other vegetable matter of economic
importance, we shall be led to believe that their usefulness
has in the past been over-estimated.

September 20 a pair of H. caliginosus was received from
Mr. F. H. Mosher, an inspector of the Board. They were
placed in a breeding jar with a larvse of Halesidota maculata
and flower head of ragweed. Another female found near the
insectary was placed in the jar three days later. The beetles
fed on the weed, eating chiefly the seeds, but did not molest
the caterpillars. A pair copulated the following day, re-
maining in coitu about three minutes. They were then
isolated, and two days later, September 26, seven eggs were
found about three inches below the surface of the ground.
Two eggs were deposited the following day, and on October
15, no more having been laid, the beetles were placed in a
wire cage near the insectary, to obtain notes on their hiber-
nation. The eggs, which were kept in the insectary, hatched
in nineteen days from the date of oviposition. Some of
these larvse have also been placed in an outdoor cage for the
winter, and an attempt will be made next year to complete
the life history of this species.

112 THE GYPSY MOTH APPENDIX.

THE SPECIES OF PODISUS OCCURRING
THE UNITED STATES.

BY A. H. KIRKLAND, M.S,

As one of the natural checks upon the undesirable increase
of many species of insects, the " soldier bugs" of the genus
Podisus are of considerable economic importance. Arboreal
in habits, almost entirely predatory and requiring daily a
considerable amount of fresh food, they exert an influence
which may entitle them to rank with the beneficial pre-
daceous insects of any order. When disturbed, these bugs
emit a decidedly unpleasant odor, and in their passage over
berries sometimes impart to the fruit a most nauseating taste,
a habit common to many bugs, and one that has given them
a most disreputable popular name. Yet when we consider
the fact that throughout the season of their activity these
soldier bugs are daily destroying the caterpillars that strip
our trees, the slugs that devour our potato vines and numer-
ous other species that prey upon our cultivated crops, the
occasional annoyance caused by these insects is of but trifling
importance. In our w r ork against the gypsy moth no other
predaceous insects have been so commonly noticed destroy-
ing the caterpillars, and their attacks upon other injurious
larvae have been a matter of frequent observation. During
the past four years, in connection with other work, the writer
has had many opportunities to observe the feeding habits of
our common species, and has published elsewhere, in detail,
the life history of two members of this genus. The litera-
ture upon these most interesting insects is found in several
languages and in the publications of both hemispheres. As
a large part of it is somewhat difficult of access to the general
student, it has seemed that a compilation of the known facts

PREDACEOUS BUGS. 113

concerning our native species might be of value in facilitat-
ing their identification.

THE GENUS PODISUS.

This genus was established by Herrich-Schaffer in 1853
( " Wanzenartigen Insecten," Vol. IX., p. 296), to include
a number of species having their fore femora unarmed,
which, aside from this character, would properly fall into
the genus Oanlhecona. At this time he described several
species from Brazil, and in the list given in his "Index
Hemipterorum Heteropterorum," published during the same
year, enumerates some ten species of Podisus, among which
is P. luridus Fab., which had formerly been placed in the
genera Pentatoma and Arma. No type of the genus is
designated by Herricb-Schaffer, but as P. luridus * is its
sole European representative, and was included by him in
the genus at the time of its establishment, this species may
be properly taken as the generic type. The presence of
the ventral spine excludes the species of Podisus from the
genus Arma, under which several were originally described.
Stal erected the genus Telepta in 1858 ("Bidr. Rio Jan.
Hemip.," p. 10) but later transferred the species therein
included to Podisus ("Enurn. Hemip.," 1870, p. 48). In
the latter work, loc. cit., he divided the many species of the
genus Podisus among the sub-genera Troilus Stal, Apateticus
Dall., Apo2cilus Stal, Podisus H. S. and Tylospilus Stal,
his genus Telepta being given as a synonym of the sub-
genus Podisus.

The genus Podisus may be characterized as follows :

Head nearly quadrangular ; basal segment of antenna stout,
not reaching to the anterior margin of the head ; rostrum stout.
Scutellum triangular, extending but little beyond the middle of
the abdomen, the apex reaching to or upon the membrane of the
wing. Fore femora unarmed ; fore tibia* not dilated. Second
abdominal segment with a spine of variable length extending
anteriorly.

* Professor Fernald has kindly given me a pair of P. luridus. This species is
of about the same size as P. sjrinosus, but differs from, any of the representatives of
the genus in the United States in that the humeral angles are very prominent and
rounded, almost lobate.

114 THE GYPSY MOTH APPENDIX.

A large genus, represented by many species from North,
Central and South America, the Antilles and by a single
species from Europe and Asia.

Habits.

Before presenting generalities concerning the habits of our
native species, it will be proper to say that the statements
are based upon a general knowledge of the life histories of
P. serieventris, P. placidus, P. modestus and P. cynicus.
A more intimate knowledge of the early stages of all the
species may lead to some changes in the statements here
given. It may be remarked that apparently but little at-
tention has been given by entomologists to the rearing of
these predaceous insects, probably on account of the diffi-
culty in supplying the young bugs with the fresh food they
daily require.

The insects emerge from their hibernating quarters in the
spring, at about the time the foliage appears. After feeding
for a week or more upon the most abundant caterpillars, the
eggs are laid on leaves or branches of trees. The young
bugs hatch in the course of a week or two, molt four times,
reach the imago state by midsummer, and lay eggs for a
second brood, which matures early in the fall. In passing
from the last nymph stage to that of the imago the number
of joints of the tarsi and the anteunse is increased by one.
In the case of the larger species, such as P. cynicus, there
seems to be but one brood yearly in this latitude. Farther
south the number of annual broods may be greater. Both
sexes hibernate under leaves on the ground, under the
bark of trees or in other sheltered places. The life of the
female imagoes in captivity ends soon after the eggs have
been deposited.

It has been stated, as a general rule, that the group of in-
sects to which these bugs belong "will bear watching" so
far as feeding habits are concerned. Many feed on plants,
often to an injurious extent ; some are entirely predaceous ;
while others feed on both plants and insects. The species
of Podisus whose habits have been recorded feed upon in-
sects almost entirely, and are very beneficial. It should be
admitted that Dr. Fitch (Third Report Insects of New York,

PREDACEOUS BUGS. 115

1856, pp. 335, 336) includes P. cynicus and P. spmosus
among the insects that attack the limbs of the apple, a
statement that Dr. Lintner (First Report Insects of New
York, 1882, p. 331) very properly questions. It is equally
doubtful if P. modestus attacks the grape vine, as stated by
Fitch (op. cit., p. 390) ; and it would seem possible that the
statements of Glover and Sauuders in regard to the attacks

cr

on plants by some of the above-mentioned species rest on
Dr. Fitch's authority, and not on personal observation-;.
Nearly two hundred specimens of our common species of
Podisus have been collected by the writer and his assistants
during the past four years, and in no case have any of these
insects been found feeding on plants. When confined P.
serieventris has been known to puncture the leaves of oak
("The Gypsy Moth," Forbush-Fernald, 1896, p. 402), a
performance that has been observed but once. It should,
however, be stated that a large part of the normal food of
the newly hatched bugs seems to be the sap contained in
leaves. So far as our observations extend, the nymphs after
molting once are entirely predaceous.

Beneficial insects are so worthy of attention and praise
that one may easily dilate upon their good qualities and
overlook the harm they do. To state the case fairly with
the genus Podisus, it will be proper to say that some of the
species may occasionally devour a coccinellid beetle or other
beneficial insect. Walsh has recorded a single case of the
kind ("American Entomologist," 1868, p. 13). If this habit
is a common one, we should probably have more records of
it. The worst point that the writer has observed in the
habits of the species is that when the food supply runs short
they will devour each other ("The Gypsy Moth," p. 402).
A glance over the list of insects each species is known to
destroy will show which way the balance swings. The fol-
lowing table will aid in the separation of the species occur-
ring in the United Statei :

116 THE GYPSY MOTH APPENDIX.

SYNOPSIS OK TIIK SPECIES.*

1 ^ Membrane with a distinct dark spot at tip, . . . . .2.

( Membrane without a dark spot ........ 5.

Scutellum with a dark V-shaped spot, .... acutissimus.

Scutellum without such spot, ....... 3.

^ Humeral angles produced into slender spines, . . sjnnosuft.
( Humeral angles acute but not spinose, . . . . .4.

, ^ Ventral spine very short, not reaching hind coxae, . inodestus.

I Ventral spine reaching to or upon hind coxae, . . serieventri* .

r { Lateral lobes of head longer than tylus (median lobe), . . 6.

( Lateral lobes of head not longer than tylus, . . . .8.

fi ^ Humeral angles produced into stout spines, . . . cynicus.
f Humeral angles not spinose, ... ... 7.

Humeral angles rounded, ventral spine very short, . . gillettei.
Humeral angles nearly right-angled, ventral spine long, crocatus.
Q $ Humeral angles spinose, curved toward head, . . inucroncttit*.
\ Humeral angles blunt and rounded, .... placidus.

PODISUS PLACIDUS Uhler. (Plate 1, fig. 1.)

1869, (?) Stiretrus fimbriatus Saunders, Can. Ent., vol. II ,

p. 15.f

1870, Podisus placidus Uhler, Amer. Ent., voL II., p, 203.
1870, Armaplacidum Sauuders, Can. Ent., vol. II., pp. 93, 94.
1872, Podisus placidus Lintuer, Ent. Contrib.,1., p. 150.
1872, Podisus placidus Saunders, Rep. Ent. Soe. Ont.,p. 31.
1877, rodisus placidus Riley, 9th Rep. Ins. Mo., p. 17.
1889, Podisus placidus Saunders, Ins. Inj. to Fruits, p. 342.
1895, Podisus placidus Gillette-Baker, Bull. 31, Col. Agrl.

Expt. Station, Ilemipt. Col., p. 13.
1897, Podisus placidus Kirkland, Rep. Mass State Bd. Agr.,

pp. 399-404.

1897, Podisus placidus Uhler. ibid., p. 403.
1897, Podisus placidus Kirkland, Can. Ent , vol. XXIX.,

p. 115.
1897, Podisus placidus Uhler, ibid., p. 116.

Length: male, 9 ram. ; female, 10 mm. Body ovate, yellowish
brown; ground color creamy yellow, punctate with brick red.
Head but little longer than wide, lateral margins dark brown ;
lateral lobes not longer than tylus, usually a little shorter ; tylu*
punctate laterally, nearly bare in the middle. First segment of
antennae short, yellowish, darker outwardly ; second segment

* Podisus politus Uhler (Ms.) of Uhler's check list (1886) has been suppressed as
a name for a North American species (Uhler in litt.) .

t The bibliography given for each species contains only such references as the
writer has been able to verify personally.

PREDACEOUS BUGS. 117

slender, about three times as long as first ; third segment but little
more than one-half as long as second ; fourth segment two-thirds
as long as second; fifth segment a little shorter than fourth,
dilated ; all segments, except first, pale brownish, lighter at their
outer ends. Kostrum pale yellow except at tip, reaching upon
hind coxre ; second segment longest, passing front coxas ; third
and fourth segments of nearly equal length, the latter brown.
Prouotum sparsely punctate before, densely behind, the humeral
angles ; its anterior margin ivory yellow, bordered posteriorly with
a double row of punctures ; across the surface there are several
transverse irregular wrinkles ; sides oblique, straight or but
slightly indented, with very minute teeth anteriorly. A pale cal-
lous line extends from the middle of the anterior margin to the
tip of the scutellum. Post-humeral margins slightly sinuate, pos-
terior margin bordered with an ivory-yellow line. Scutellum
reaching to the membrane, sinuate behind the middle, where it
is more densely punctate than elsewhere ; tip white. P^mbolium
and cerium,' except at base, densely punctate ; clavus and base
of corium sparsely punctate ; a brownish callous spot occurs near
the outer end of the corium ; membrane pale bronze, translucent.
Connexivum pale yellowish with faint black markings at incisures.
Under-surf ace sulphur yellow with minute black markings laterally
in some specimens. Ventral spine reaching the hind coxre, ivory
yellow. Legs rufous ; tarsi brown. A black dot occurs at the tip
of the osteolar canal and another in front of each eye.

Habits.

The life history of this species has been detailed in the
last annual report of this committee. Briefly stated, the
imagoes hibernate and appear early in the spring. They
attack the larvae of Qlisiocarnpa americana Harr., and aiter
feeding for about a fortnight upon these and other insects,
lay their eggs on the under sides of leaves or on twigs.
From fifty to sixty eggs are laid by a single female. The
eggs hatch in about ten days, and the red and black nymphs
feed on the juices of the leaves for about a week, when the
first molting takes place. From this time on the insects are
predaceous. The second and third molts take place in
twelve and ten days respectively ; in the last nymph stage
the head, thorax and wing-pads are intense pitchy black, the
abdomen dark red, margined with a series of black spots,
one on each sesrment. On the dorsuni there are four black

118 THE GYPSY MOTH APPENDIX.

spots placed in a longitudinal row. The last molt takes
place in about three weeks.

The imagoes of the summer brood appear during July and
those of the fall brood in September. While feeding upon
the tent caterpillars in the spring this bug is frequently
devoured by two spiders, Epeira strix and Phidippus mulli-
formis, which are common occupants of the caterpillar webs.

The list of insects P. placidus is known to destroy in-
cludes Pteronus ribesii Scop. (Saunders, Can. Ent., 1870,
pp. 93, 94), Euvanessa antiopa Linn., Hyphantria cunea
Drury, Orgyia leucostigma S. and A., 0. definita Pack.,
Porthetria disjjar Linn., Clisiocampa amerlcana Harr., C.
disstria Hbn. (Kirkland, Report Massachusetts State Board
Agriculture for 1896, p. 404.)

Distribution. Canada, Massachusetts, New York,* Mich-
igan, f Colorado.

PODISUS GILLETTEI Uhler. (Plate 1, fig. 6.)

1895, Podisus gilletlei Uhler, Gillette-Baker, Bull. 31, Col. Agrl. Expt.
Station, Hemip. Col., pp. 12, 13.

Prof. C. P. Gillette has been so kind as to send me the
type and only known specimen of this beautiful species. Its
prominent characters are :

Length, 14 mrn. Body ovate, like P. placidus, but much larger.
Upper-surface dull olive colored, punctate with black. Head
quadrangular, lateral lobes longer than tylus, but not as long as iu
P. cynicus. The sides of the tylus are margined anteriorly with
yellowish. The entire upper surface of the head, aside from the
preceding, is heavily punctate with black. First segment of an-
tennae not extending beyond lateral margin of head, yellowish ;
second segment hardly longer than head, testaceous; third seg-
ment two-thirds as long as second ; fourth and fifth segments of
nearly equal length, each about three-fourths as long as second,
and, in common with the third segment, black except at base,
which is yellowish. Rostrum of medium size, not as short as in
P. cynicus, reaching upon middle coxne. Second segment of ros-
trum reaching on the fore coxae ; third and fourth segments of
nearly equal length; fourth segment piceous.

* Specimen in Dr. Lintner's collection, labelled " Keene Valley, N. Y , July 4,
1890."
f Specimen in Museum of Comparative Zoology collection, labelled " Mich."

PREDACEOUS BUGS. 119

Prouotal margins very oblique, with finely incised edges anteri-
orly, with a broad ivory-yellow baud, which diminishes at the
humeral angles, which are very obtuse and rounded. The black
puncturing on the anterior part of the prouotum is very dense ;
that on the posterior part less dense, arranged in irregular trans-
verse lines. Scutellum but slightly sinuate, most densely punc-
tured at base, and with a small callous spot in each basal angle.
A fine callous line extends longitudinally through the pronotum
and scutellum. Corium densely punctate ; membrane bronzed,
without apical spot. Couuexivurn ivory yellow, with faint black
markings interiorly at segrnental sutures. These markings do not
reach the lateral edge of abdomen. Under-surface pale yellowish
brown, punctate with darker brown. Abdominal spine very short,
nearly obsolete. Legs of same color as uuder-surface, darkening
on tibiae to brown. Tarsi dark brown, hairy.

The stout rostrum indicates that this species has preda-
ceous habits.

PODISUS MODESTUS (Dallas). (Plate 1, fig. 9.)

1851, Anna modesta Dallas, List, part I., pp. 101, 102.
1856, Anna modesta Fitch, 3d Rep. Ins. N. Y., p. 390.

1869, Arma modesta Walsh, Can. Ent., vol. II., p. 33.

1870, Podisus modestus Stal, Enum. Heniipt, part I., p. 51.

1872, Arma modesta Lintner, Ent. Contrib., I., p. 150.

1873, Arma modesta Riley, 5th Rep. Ins. Mo., p. 133.

1875, Podisus modestus Uhler, Bull. 5, vol. I., U. S. Geol. Surv.

Terr., p. 283.

1876, Podisus modestus Glover, Manuscript Notes Heniipt. Het,

p. 60.

1880, Podisus modestus Distant, Biol. Cent. Am. Rhync., vol. I.,
pp. 38, 39, pi. IV., fig. 4.

1884, Podisus modestus Fletcher, Can. Ent., vol. XVI., p. 215.

1885, Podisus modestus Fletcher, Rep. Ent. Soc. Ont., pp. 22, 77.
1889, Podisus modestus Lintner, 5th Rep. Ins. N. Y., p. 170.

1889, Arma modesta Saunders, Ins. Inj. to Fruits, p. 290.

1890, Podisus modestus Lintner, 6th Rep. Ins. N. Y., p. 189.

1890, Anna modesta Packard, 5th Rep. U. S. Ent. Com., p. 164.

1891, Podisus modestus Lintner, 7th Rep. Ins. N. Y., p. 353.

1892, Podisus modestus Riley-Howard, Insect Life, vol. IV.,

p. 123.
1895, Podisus modestus Gillette-Baker, Bull. 31, Col. Agrl. Expt.

Station, Heniip. Col., p. 13.
1897, Podisus modestus Kirkland, Can. Ent., vol. XXIX., p. 115.

Length : male, 9.5 mm. ; female, 10.5 mm. One of the smallest
of our native species. Upper-surface densely and evenly punctate

120 THE GYPSY MOTH APPENDIX.

with light brick red. Head much longer than wide, nearly trun-
cate in front. The lateral lobes in a few specimens I have ex-
amined are a trifle longer than the tylus, but this seerns to be an
exception ; outer margin of lateral lobes embrowned. Eyes very
dark brown ; ocelli minute, near occiput. First segment of au-
tennffi very short, hardly reaching lateral margin of head ; second
segment slender, relatively short, but little over three times as
long as first ; third segment about three-fourths as long as second ;
fourth segment nearly as long as second ; fifth segment longer .
than third, but a little shorter than fourth ; all joints reddish or
pale brown. Rostrum stout, reaching upon, sometimes to, pos-
terior margin of hind coxa? ; second segment the longest, third
and fourth of equal length, the latter dark reddish brown. Pro-
notum deeply indented at the sides, margined with a fine yellowish
white line, within which the puncturing is densely massed ; an-
teriorly on the lateral margins there are several minute teeth ;
prouotal callosities obscure, thickly punctate outwardly. At the
humeral angles the punctures are massed into a reddish spot, the
angles being acute but not spiuose. Scutellum sinuate, bare at
apex, which reaches to the membrane ; in nearly all specimens
examined there is a minute bald spot at each basal angle of
scutellum. Coriurn and embolium tinged with scarlet at their
junction with membrane, which is bronzed and bears a dark-green
marking at the tip. Under-surface pale yellowish, punctate with
red, and bearing a row of four minute dots on the median line and
two rows of similar dots laterally. Ventral spine very short, not
reaching hind coxre. Legs rufous.

Distribution. Canada, Maine, Massachusetts, New York,
Illinois, Georgia, Dakota, Nebraska, Colorado, Mexico.

The only species resembling P. modestus is the light
variety of P. serieventris, which sometimes approaches the
darker forms of the former species. The deeply sinuate
humeral angles, the red marking at the tip of the cerium, the
light-colored tergurn, the short ventral spine and short sec-
ond segment of antennae, -- are characteristic of modestus,
and will serve to distinguish it.

Habits.

This species is very common in May, feeding on tent
caterpillars ( Olisiocampa americana Harr. ) . At the Museum
of Comparative Zoology, Cambridge, there are several speci-
mens which were found under leaves by Mr. Jacob Boll in

PREDACEOUS BUGS. 121

the winter of 1872-73, thus proving that the insect hiber-
nates as an imago. Different stages of the nymphs have
been reared to imagoes at the insectary of the gypsy moth
committee ; but, owing to the amount of work involved, we
have made no attempt to carefully follow the entire round
of life, which apparently does not vary materially from that
of serieventris. The imagoes are abundant in the spring,
again in midsummer and also in September and October,
and there can be no doubt that the species is here double-
brooded. P. modeslus is less common than serieventris or
placidus, and, so far as my experience goes, is more fre-
quently found on bushes and low-growing plants than on
trees. In feeding habits it shows the same voracity as
serieventris, and preys upon larva? of all sizes. It has
been rec'orded as destroying Haltica bimarginata Say (Lint-
ner, Fifth Rep. Ins. N. Y., 1889, p. 170), Haltica chalybea
III. (Liutner, Sixth Rep. Ins. X. Y., 1890, p. 189), Hemileuca
maia Drury (Lintner, Eut. Coutrib., I., 1872, p. 150),
Clisiocampa americana Harr. (Kirklaud, Can. Ent., 1897,
p. 115), LygoBonematus erichsonii Hartig (Fletcher, Can.
Ent., 1884, p. 215). In Professor Feruald's collection there
is a specimen of P. modest us taken feeding on a leaf hopper
at Amherst, Mass., May 28, 1890.

In September, 1896, Mr. Robert Cooley took a nymph of
this bug at Brewster, Mass., feeding on the pupa? of the
"yellow-headed fire worm," Terns minuta. The imago
developed September 20. The writer has found modest us
feeding on gypsy moth larvae during the past summer at
Saugus, Mass. A minute hyuienopterous parasite, Tehno-
mus podisi Ashm., has been reared from the eggs of this
bug ( Insect Life," IV., p. 123, 1892).

PODISUS FALLENS (Stal).

1859, Anna pollens Stal, Freg. Eug. Resa, p. 222.
1870, Podistis pallens Stal, Eaurn. Hemipt., part I , p. 51.
1875, Podisus pallens Uhler, Bull. 5, vol. I , IT. S. Geol.
Surv. Terr., p. 282.

Stal's description of this species may be translated as
follows :

122 THE GYPSY MOTH APPENDIX.

Whitish yellow, somewhat punctate with bi'ownish dots, more
finely and less densely (punctate) beneath; antennae darker
towards the apex ; posterior angles of thorax produced, sub-
acute ; scutellum not punctate at the lowest part of the apex ;
abdomen with each segment margined with a minute spot above
and below at base and at apex, and with spots placed in series on
both sides ; femora tawuy, with an apical dot.

I have been unable to obtain an example of this species
and have not included it in the synopsis. The insufficiency
of the original description was long ago pointed out by Pro-
fessor Uhler in the following words : " The small differences
in the lateral angles of the pronotuin and in puncturing do
not seem to me suffiicent to separate this from P. modestus."

The specimens from which the original description was
prepared were collected in California.

PODISUS CROCATUS Uhler. (Plate 1, fig. 3.)

1878, Podisus cynicus, var. obscuripes (Uhl. Ms ) Riley, Kept.

U. S. Dept. Agr., p 245.
1884, Podisus * crocatus (Uhl. Ms.) Hageu, Can. Ent., vol. XVI.,

p. 40.
1897, Podisus crocatus Uhler, Trans. Md. Acad. Sc., pp. 384-386.

Through the kindness of Mr. Samuel Henshaw I have had
the privilege of examining several representatives of this
species at the Museum of Comparative Zoology, Cambridge,
Mass. Professor Uhler has also kindly given me a specimen
from Vancouver Island. I have nothing to add to Professor
Uhler's excellent description of the species. Its prominent
characteristics are :

Length, 15 mm. Body robust, reddish yellow, heavily marked
with dark-green punctures. Lateral lobes of head longer than
tylus, and bordered outwardly with a fine dark-green line. First
segment of antennae stout, reaching about three-fourths the dis-
tance between eye and anterior margin ; second segment about
three times as long as first ; third segment two-thirds as long as
second ; fourth segment one-third longer than third ; fifth segment
a trifle longer than third. Rostrum stout, reaching to hind coxaa ;
first segment thick ; second segment but little longer than first ;

* Misprinted " Podiscus."

PREDACEOUS BUGS. 123

third and fourth segments each nearly as long as first. Sides of
pronotum coarsely serrate anteriorly ; humeral angles nearly right
angled, dark green. Scutellum punctate with dark green, reach-
ing to the membrane. Corium of same color as scutellum ;
membrane bronze brown, extending beyond tip of abdomen.
Conuexivum orange, marked with dark green at the iucisures.
Under-side yellowish, punctate with brick red laterally. Legs
amber colored, darkening toward the tarsi. Ventral spine stout,
nearly passing the hind coxye.

In size this species resembles P. cynicus, from which it
may be distinguished by its orange-colored body with dark-
oreen markino-s, and humeral angles which are not as acute

t* ~ 7

as in that species.

Distribution. Vancouver Island, Washington, Oregon,
California.

Habits.

In July, 1882, Mr. Samuel Henshaw collected a number
of imagoes of this species and three nymphs near Loon
Lake, Washington. These insects were feeding on the

C O

larva of Neopliasia menapia Feld. Aside from a darker
coloration, the nymphs bear a striking resemblance to those
of P. cynicus. Being certainly an immature stage of a large
Podisus, taken at the same time and place with the imagoes
of P. crocatus, there can be but little doubt that they are the
nymphs of this species, and may be described as follows :

Podisus crocatus (?) nymph.

Length, 11 to 14 mm. Body compact, very stout, widest at
middle of abdomen. Head and thorax heavily marked with dark
bronze green. Abdomen thickly covered with scarlet dots. Head
distinctly emarginate in front, edges at least bordered with dark
green ; a scarlet line extends along the inner margin of the lateral
lobes, and also on median line from between the, eyes backward to
pronotum. First segment of antennae stout, slightly projecting
beyond the lateral margin of the head ; second segment nearly
us long as third and fourth taken together, these latter being of
nearly equal length ; all segments dark bronze green. Rostrum very
stout, extending to middle coxte ; tip dark brown, horny. Edges
of prothorax, scutellum and wing-pads heavily bordered with dark
green. Irregular scarlet markings occur on either side of the
dorsal groove of the prothorax, on the scutellum and on the wing-

124 THE GYPSY MOTH APPENDIX.

pads ; the extent of these markings varies inversely with that of
the green ones. One specimen has no red on the scutellum or
wing-pads, and but two small spots on the prothorax ; while on the
other specimens the red predominates. On the dorsum of the
abdomen there is a longitudinal row of four transverse dark-green
spots, while around the margin at the middle of each segment
there is a semi-elliptical spot of dark green ; included in each of
these marginal spots is a much smaller spot of similar shape, pale
buff in color. Under-side pale buff, dotted with scarlet. Femora
and tibiae reddish brown ; tarsi dark green.

In a note on the enemies of Neopliasia menapia, Hag-en
has written : " Podisus crocatus Uhl. (Ms.) is a very eage 1 '
enemy of the pupa and the caterpillar before pupating, when
it is very sluggish. The P. crocatus was everywhere com-
mon in the devastated forests, and observed in the act of
sucking caterpillars" (Can. Eut., XVI., p. 40).

The above, and Riley's record of this species * feeding on
Diapheromem femorata Say, are the only reference3 to the
habits of this insect I have been able to find.

* Given as P. cynicus var. obsctiripes, which name Professor Uhler writes rne he
has rejected in favor of P. crocatus.

PREDACEOUS BUGS. 125

PODISUS CYNICUS (Say). (Plate 1, fig. 7.)

1831, Pentatoma cynica Say, Descr. New. Sp. Het. Hemip. of

N. A., p. 3, New. Harm., Ind.*

1851, Arma grandis Dallas, List, part I., pp. 96, 97.
1856, Arma grandis Fitch, 3d Rep. lus. N. Y., p. 335, pi. 2,

fig. 7.

1856, Anna bracteata, Fitch, ibid., p. 336.

1857, Pentatoma cynica Fitch, 4th Rep. Ins. N. Y., p. 757 (re-

print of Say's description).

1859, Pentatoma cynica Say, Com pi. Writ., vol. L, p. 312.
1867, Podisus grandis Stal, Ofvers. Yet. Ak. Furh., p. 497.
1870, Podisus grandis Stal, Enum. Hemipt., part I., p. 49.
1870, Podisus bracteatus Stal, ibid., p. 54.
1870, Podisus cynicus Stal, ibid., p. 54.

1874, Arma grandis Glover, Rep. U. S. Dep. Agr., p. 123.

1875, Podisus cynicus Glover, Rep. U. S. Dep. Agr , p. 118, fig. 8.

1875, Podisus cynicus Uhler, Bull. 5, vol. I., U. S. Geol. Surv.

Terr., p. 282.

1876, Podisus cynicus Glover, Manuscript Notes Hemip. Het.,

p. 59, pi. II., fig. 29.
1876, Arma bracteata Glover, ibid., p. 60.

1876, Podisus cyniciis Uhler, Proc. Bost. Soc. Nat. Hist., p. 370.

1877, Podisus cynicus Glover, Entomological Index, pp. 8, 58.

1878, Podisus cynicus Riley, Rep. U. S. Dep. Agr., p. 245.
1878, Podisus cynicus Uhler, Bull. 2, vol. IY., U. S. Geol. Surv.

Terr., p. 504.

1882, Podisus cynicus Lintner, 1st Rep. Ins. N. Y., p. 331.
1884, Podisus bracteatus Lintner, Can. Ent, vol. XVI., p. 182.
1884, Podisus cynicus Lintner, ibid.

1884, Podisus cynicus Uhler, Standard Nat. Hist., pp. 291, 292.

1885, Podistis cynicus Lintner, Rep. Ent. Soc. Ont., p. 13.
1885, Podisus cynicus Riley, 4th Rep. U. S. Ent. Com., p 97.
1890, Podisus bractealus Cockerell, Can. Ent., vol. XXII., p. 59.

1890, Podisus cynicus Lintner, Pop. Gardening, p. 198.

1891, Podisus cynicus Lintner, 7th Rep. Ins. N. Y., p. 356

1894, Podisus cynicus Fernald, Rep. Mass. State Bd. Agr., p. 260.

1895, Podisus cynicus Gillette-Baker, Bull, 31, Col. Agrl. Expt.

Station, Hemip. Col., p. 12.

1895, Podisus bracteatus Gillette-Baker, ibid.

1896, Podisus cynicus Kirkland, The Gypsy Moth, Forbush-

Fernald, pp. 392, 394, 402.

1897, Podisus cynicus Kirkland, Can. Ent., vol. XXIX., p. 115.

Length: male, 14.6 mm. to 17.8 mm.; female, 15 mm. to
18.8 mm. Tawny yellow, punctured with brick red or reddish-
brown dots. Head longer than wide ; lateral lobes longer thau

* This rare pamphlet is iii the library of the Boston Society of Natural History.

126 THE GYPSY MOTH APPENDIX.

tylus. Eyes dark brown ; ocelli vermilion, in rear of eyes, nearer
median line. First segment of antennae stout, extending about
three-fourths of the distance between the eye and anterior margin
of head ; second segment a little more than three times as long as
first ; third segment two-thirds as long as second ; fourth segment
a trifle longer than third ; fifth segment of about the same length
as fourth. Rostrum very stout, reaching to hind coxa? ; first seg-
ment wide and thick ; second segment one-third longer than first,
enlarging at its junction with third segment, which is of about the
same length as first; fourth segment a little shorter than third,
terminating in a blunt brown point. Prouotum and scutellum of
same color as head. Sides of prouotum sinuate, with fine gran-
ular teeth anteriorly ; humeral angles produced into stout acute
spines. The callous spots on the anterior part of prouotum bear
one or more small green markings ; in some specimens there are
small spots of this color at the anterior angles of the pronotum
and at the inner ends of the callous spots. Scutellum sinuate
behind its middle, reaching slightly upon the membrane. Corium
of same color as scutellum ; membrane bronze brown, extending
beyond tip of abdomen. Connexivum orange, marked with black
at the incisures. Under-surface pale yellow, dotted more or less
with red. Legs of same color as under-surface, darkening slightly
in some specimens towards the tarsi. Ventral spine very stout,
reaching to middle coxae.

Distribution. Massachusetts, New York, Pennsylvania,
Maryland, Illinois, Wisconsin, Dakota, Nebraska, Missouri,
Colorado, Arizona.

Podisus bractealus, as described by Fitch, differs from
cynicus only in certain small green markings on the prono-
tum, scutellum and wing-covers. In our collection there is
a series of thirty-seven specimens which shows nearly all the
variations between the two species as described. Being
unable to distinguish between the species, I tried to obtain
specimens of bracteatus from several sources, but was unable
to do so. In this difficulty I wrote to Professor Uhler, and
found that he also was not familiar with this species. Since
that time he has very kindly gone to the trouble to examine
the specimen of bracteatus in the Fitch collection at the Na-
tional Museum, and has decided that it is but a variety of
Say's cynicus. Glover in 1876 expressed the opinion that
bracteatus was but a variety of cynicus (Manuscript Notes

PREDACEOUS BUGS. 127

Hemip. Het., p. 60), an opinion also held by Dr. Lintner
(Report Entomological Society, Ontario, 1885, p. 13), but
which appears to have been overlooked by later writers.
Aside from the variations in the green markings on the

O O

thorax previously referred to, the color of the punctures on
the upper-surface ranges from brick red to dark brown. The
only aberrations in form that I have seen are two specimens,
one of which has both humeral angles blunted off and actu-
ally emarginate, the other having the right humeral angle
normal, the left being rounded. Both these insects were
bred from nymphs, and their peculiarities of structure may
be due to defective nutrition or to some accident at the time
of the last molt, while the body was still soft.

Habits.

The imagoes of this species hibernate under leaves. At
the Museum of Comparative Zoology, Cambridge, there are
several specimens collected by Mr. Boll during the winter
of 1872-73. These were sifted out from a quantity of
leaves raked from the ground. The eggs and early nymph
stages are unknown to the writer. Nymphs in the last stage
have been taken frequently during June, July and August,
and are known to feed on the larvae of the gypsy moth.
They may be described as follows :

Podisus cynicus nymph.

Length, 10 mm. ; greatest width, 8 mm. Body compact, some-
what elliptical iii outline ; head deeply inserted in the thorax.
Posterior angles of thorax produced for a short distance along
the sides of the abdomen. General color of head and thorax
pale yellowish brown, sometimes marked with red. A fine dark
seal-brown line extends around the margin of the head, thorax
and wing-pads, and borders the tylus. From near the middle of
the inner margin of each wing-pad a fine dark-brown line extends
obliquely outward and backward to the outer margin, enclosing a
somewhat diamond-shaped area, and marking the anterior margin
of the future wing membrane. The median sulcus of the pro-
thorax and scutellum is bordered with dark brown, and the sur-
face of the thorax is finely punctured with faint brown dots. On
either side of the dorsal sulcus of the prothorax there is a short,
irregular, transverse black line, extending obliquely backward

128 THE GYPSY MOTH APPENDIX.

toward the lateral margin. Abdomen brick red, bordered with
heavy black line. At the middle of the lateral margin of each
segment there is a well-defined semi-elliptical yellowish-brown
spot, bordered with black. There are four more or less confluent,
transverse dark-brown spots on the dorsum , Under-surf ace of
head and thorax amber colored ; color of abdomen somewhat
lighter than that of the upper-surface. Antennas four-jointed,
black ; first segment stout, partially retracted beneath the edge of
the head ; second segment slightly flattened, widened toward its
outer end and four times as long as the first ; third and fourth
segments of nearly equal length, the latter being constricted at
each end. Femora amber colored ; tibias with three equidistant
longitudinal ridges, pale brown and sparsely hairy ; tarsi two-
jointed, dark brown and hairy.

From the late appearance of the nymphs, it is probable
that the species has but one annual brood in this region.
Both nymphs and imagoes are rapacious feeders, their stout
beak being a very formidable weapon. The insect attacked
is impaled by a sudden thrust of the setae, which hold it
firmly, and in a few minutes the body fluids are sucked out.
In killing large insects the setae are sometimes wrested from
the rostrum, but are readily replaced by the bug. The setre
can be moved by muscles at their base independent of the
rostrum, and are armed with formidable reflexed spines.

The records of insects destroyed by this species include
DiapJieromera femorata Say (Riley, Rep. U. S. Dep. Agr.,
1878, p. 245), Podisus serieventris Uhl. (Kirkland, "The
Gypsy Moth," Forbush-Fernald, 1896, p. 402), Doryphora
decem-lineata Say (Glover, Ent. Index, 1877, p. 8), Portlte-
tria dispa.r Linn. (Fernald, Rep. Mass. State Bd. Agr., 1894,
p. 260), Alet'm argillacea Hbn. (Riley, Fourth Rep. U. S.
Ent. Com., 1885, p. 97), Pteronus ribesii Scop. (Liutner,
Can. Ent., 1884, p. 182).

PREDACEOUS BUGS. 129

PODISUS SEEIEVENTRIS Uhler. (Plate 1, %. 2.)

1870, Podisus serieventris Uhler, Prou. Bost. Soc. Nat. Hist., p. 94.
1876, Podisus serieventris Uhler, Proc. Bost. Soc. Nat. Hist., p. 370.
1892, Podisus spinoszts~Fernald, Rep. Mass. State Bd. Agr., p. 298. '
1892, Podisus spinosus Fernakl, Bull. 19, Mass. Hatch Expt.

Station, p. 116.
1892, Podisus spinosus Riley-Howard, Insect Life, vol. IV., p. 354.

1894, Podisus serieventris Fernald, Rep. Mass. State Bd. Agr.,

p. 260.

1895, Podisus serieventris Gillette-Baker, Bull. 31, Col. Agrl.

Expt. Station, Heniipt. Col., p. 13.

1896, Podisus serieventris Kirkland, The Gypsy Moth, Forbush-

Fernald, pp. 393-403.

1897, Podisus serieventris Kirkland, Can. Ent., vol. XXIX.,

p. 115.

Length: male, 10-11 mm.; female, 11-12 mm. Upper-surface
pale yellowish, heavily punctate with dark brown. Head trun-
cate anteriorly, densely punctate on its anterior part. Eyes dark
brown ; ocelli minute, reddish, in rear of eyes. First segment of
antennae short, blackish outwardly, scarcely projecting beyond the
lateral margin of head ; second segment spread over with black,
slender, dilated at apex, about four times as long as first ; third
segment a little over half as long as second ; fourth segment two-
thirds as long as second, and with the third generally spread over
with black ; fifth segment a little longer than fourth, reddish
brown. Rostrum of medium thickness, reaching to hind coxas ;
the first, third and fourth segments of nearly equal length, the
second the longest, reaching to posterior margin of fore coxae.
Prouotum finely toothed anteriorly, indented laterally, but not as
much as in modestus. The punctures are massed at the anterior
and humeral angles into four blackish spots. Humeral angles
acute, but not spiuose, often slightly curved backward ; on the
pronotum of many specimens there are fine transverse wrinkles.
Scutellum of same color as pronotum, less densely punctate at
tip, which is sometimes whitish ; at the basal angles in some
specimens there is a small bald whitish spot. Coriuin more
densely punctate than embolium ; membrane bronzed, with a dark
spot at the tip. Under-surface pale yellowish, marked and
clouded with darker shades and sparingly punctate with reddish ;
on the middle of the last segment there is a round or oval black
spot, above which in a longitudinal row there are often three
minute black spots ; laterally there are two rows of small black
spots, occurring as follows : one on the middle of each segment,
near conuexivuni, and one on the anterior margin of the third to

130 THE GYPSY MOTH APPENDIX.

sixth segments inclusive, this latter row being equidistant between
the ventral row and the conuexivum ; there is a large black dot
at the tip of the osteolar canal and a smaller one on the pleurae
above each of the coxae. Legs rufous ; femora with two or three
black clots near apex. Ventral spine ivory white, reaching upon
the hind coxae.

Distribution. Maine, Massachusetts, New York,* New
Jersey,f Minnesota, Colorado.

Habits.

Perhaps on account of its obscure coloring and active

flight this species may be better protected from bird enemies

than its congeners. Be that as it may, serieventris in this

region is by far the most common representative of the

genus. Hibernating as imagoes, the insects appear early in

the spring, sometimes in April, and by the latter part of

May an inspection of the webs of the tent caterpillar will

show numbers of these bugs breaking their winter's fast

upon the inmates of these webs. After a week or more

spent in feeding, mating occurs, } and in a few days the

female deposits her eggs in two or three clusters on the un-

der-sides of leaves or on small branches. From fifty to

sixty caldron-shaped eggs are laid by each female, and in

about eight or ten days' time the gaily colored nymphs emerge

from the egg-shells and commence feeding on the sap of

leaves. If weather conditions are favorable, the first molt

takes place in four or five days, and the nymphs wander

forth in search of insects. These tiny creatures, not over

4 mm. in length, will destroy caterpillars many times larger

than themselves. The second molting occurs about ten days

after the first, and the third about six days later than the

second. The red and black nymphs feed almost continually

during this stage, and boldly attack the largest larvae. From

twelve to seventeen days elapse before the last molt. By

midsummer the eggs for a second brood are laid, the imagoes

of which appear in August and September. In 1895 the

data concerning the times at which the imagoes and nymphs

* In Dr. Lintner's collection.

f Specimens from Prof. J. B. Smith.

J These insects frequently mate in the fall (" The Gypsy Moth," p. 403).

PREDACEOUS BUGS. 131

appeared seemed to indicate the occurrence of three annual
broods. There are certainly two broods each year in this
region. The time at which different individuals of this spe-
cies appear varies to such a degree that imagoes may be
taken during every month from April to October, and only
by rearing can we get at the actual number of broods. As
recorded elsewhere, the writer has reared two broods be-
tween the latter part of June and the last of September.

This species is known to feed upon the following larvae :
Porthetria dispar Linn. (Feruald, Rep. Mass. St. Bd. Agr.,
1892, p. 298), Euvanessa antiopa Linn., Hyphantria cunea
Drury, Attacus promethea Drury, Glisiocampd americana
Harr., C. disstria Hbn., Paleacrita vernata Pack.; in con-
finement we have reared it upon Cimbex americana Leach,
Datana ministra Drury, Attacus cecropia Linn., Telea poly.
phenms Cram., Anisota senatoria S. and A., Dryocampa
rubicunda Fabr., Tolype velleda Stoll, Rhynckagrotis alter-
nata Grote, Noctua c-nigrum Linn. P. serieventris has been
known as imago to kill the nymphs of its own species and
of P. cynicus. In one case it was seen to feed on an imago
of Menecles insertus Say (Kirklaud, "The Gypsy Moth,"
Forbush-Fernald, 1896, p. 402).

PODISUS SPINOSUS (Dallas). (Plate 1, fig. 4.)

1851, Arma spinosa Dallas, List, part I., p. 98.
1856, Arma spinosa Fitch, 3d Rep. Ins. N. Y., p. 336.
1866, Arma spinosa Glover, Rep. U. S. Dep. Agr., p. 43.

1868, Arma spinosa Walsh-Riley, Amer. Ent., vol. I., pp. 13, 14,

37, 46, 59.

1869, Arma spinosa Riley, 1st Rep. Ins. Mo., pp. 77, 89, 113.

1869, Arma spinosa Walsh, Can. Ent, vol. II., p. 33.

1870, Arma spinosa Riley, 2d Rep. Ins Mo., p. 32.
1870, Arma spinosa Shinier, Am. Nat., p. 98.

1870, Podisus sjrinosiis Stal, Enum. Hemipt, part I., p. 51.

1871, Arma spinosa Kridelbaugh, Rep. la. State Hort. Soc.,

pp. 167,168.
1871, Arma spinosa LeBaron. 1st Rep. Ins. 111., pp. 64, 66, 102.

1871, Podisus spinosus Uhler, U. S. Geol. Surv. Terr. (Hayden),

p. 395.

1872, Arma spinosa Lintner. Ent. Contrib., I., p. 150.

1872, Arma spinosa Riley. 4th Rep. Ins. Mo., p. 20.

1873, Arma spinosa LeBaron 3d Rep. Ins. 111., p. 184.

1874, Arma spinosa Glover, Rep U. S. Dep. Agr., p. 123.

132 THE GYPSY MOTH APPEXDIX.

1874, Arma spinosa Lintner, Count, Gent,, p. 471.

1875, Podisus (Arma) spinosus Glover, Rep. U. S. Dep. Agr.,

p. 118, fig. 9.

1875, Arma spinosa Riley, The Garden (London), vol. VIII.,
p. 71.

1875, Podisus sp^?^os^<s Uhler, Bull. 5, vol. I., U. S. Geol. Surv.

Terr., p. 282.

1876, Podisus spijiosiis Glover, Manuscript Notes Heniipt Het.,

p. 60.

1877, Podisus spinosus Glover, Entomological Index, pp. 8, 58.

1878, Arma sjrinosa Riley, Rep. U. S. Dep Agr., p. 245.

1878, Podisus spinosus Thomas, 2d Rep. Ins. 111., p. 218.

1879, Arma (Podisus) spinosus Comstock, Rep. U. S. Dep. Agr.,

p. 289.

1880, Podisus spinosus Fuller, Anier. Ent, voL III., p. 190.
1880, Arma spinosa Packard, Guide to Study of Ins., p. 547.
1882, Podisus spinosus Lintner, 1st Rep. Ins. N. Y., p. 331.
1884, Arma spinosa Murtfeldt, Rep. U. S. Dep. Agr., p. 417.

1884, Arma S2nnosa Osborn, Can. Ent., vol. XVI., p. 151.

1885, Podisus spinosus Lintner, 2d Rep. Ins. N. Y., p. 146.
1885, Arma spinosa Osborn, Rep. Ent. Soc. Ont., p. 34.

1885, Podisus S2rinosus Riley, 4th Rep. U. S. Ent. Com., pp. 97, 98.

1886, Podisus spinosus Riley, Rep. U. S. Dep. Agr., p. 527.

1887, Podisus spinosus Riley, Shade Trees and their Insect De-

foliators, p. 45.

1889, Podisus spinosus Saanders, Ins. Inj. to Fruits, p. 73.

1890. Podisus spinosus Liutuer, 6th Rep. Ins. N. Y., p. 137.
1890, Podisus spinosus Packard, 5th Rep. U. S. Ent. Com., p. 194.
1890, Podisus spinosus Riley, 5th Rep. U. S. Ent. Com., p. 252.
1892, Podisus spinosus Riley-Howard, Ins. Life, vol. IV., p. 124.

1892, Podisus sjnnosus Riley, Rep. U. S. Dep. Agr., p. 167.

1893, Podisus spinosus Ashmead, Bull. 45, U. S. Xat. Mus.,

Proctotrypidte, pp. 159, 163.

1893, Podisus S2)inosus Lintner, 8th Rep. Ins. N. Y., pp. 238,300.
1893, Arma spinosa Lintner, 9th Rep. Ins. N. Y., p. 457.

1895, Podisus sinnosus Gillette-Baker, Bull. 31, Col. Agrl. Expt.

Station, Hemipt. Col., p. 13.

1896, Podisus spinosus Chittenden, Year Book U. S. Dep. Agr.,

p. 346.

1897, Podisus spinosus Howard, Bull. 5, Tech. Ser., Div. Eut.,

U. S. Dep. Agr., Ins. Parasitism, p. 8.

Length, 11 to 14 mm. Upper-surface yellowish, so heavily
punctured with reddish or dark brown as to give the insect a
general dull-brown color. Head nearly truncate in front ; in some
specimens the lateral lobes are a trifle shorter than tylus ; punct-
ures very close together on lateral lobes, more scattering on tylus.
Eyes dark brown ; ocelli minute, red, in rear of eyes and near the
anterior margin of prouotum. Antennae slender ; first segment

PREDACEOUS BUGS. 133

short, scarcely projecting beyond the lateral margin of head, pale
brown on its outer lateral surface ; second segment slender, en-
larging at its apex, four times as long as first, rufous at base,
darkening toward apex ; third segment about two-thirds as long
as second, and of same color ; fourth segment a little longer than
third, similarly colored ; fifth segment as long as third, rufous,
sometimes tinged with brown at the apex. Rostrum stout, reach-
ing to hind coxa? ; first segment thick, half as long as upper-sur-
face of head ; second segment one-half longer than first, nearly
passing anterior coxae ; third segment a trifle longer than first ;
fourth segment of same length as first, embrowned at tip. Sides
of pronotum indented, with fine granular teeth anteriorly ; humeral
angles often sinuate posteriorly and produced into long slender
spines, which are frequently tipped with dark brown or black.
The puncturing is closely massed at each anterior angle of the
pronotum and in a small spot at the outer end of the pronotal
callosities. A fairly well-defined dorsal line extends from the
anterior margin of the prouotum to the tip of the scutellum.
Scutellum of same color as prouotum, reaching to the membrane,
less densely punctured toward the tip. Corium of same color,
generally tinged with red near the cuueus ; membrane translucent
with a brownish spot at the tip. Connexivum pale orange, with
large black markings at each incisure ; in the middle of these
markings there is usually a minute white spot. Under-side pale
yellowish, punctate sparingly with red or brown ; on the middle
of the last segment there is a large oval black spot, anterior to
which on some specimens there is a minute black dot ; a small
black dot occurs on the third, fourth, fifth and sixth segments ;
these dots form a row which is equidistant between the median
line and the lateral margin ; osteolar canal tipped with a black
dot. Legs of same color as abdomen, femora generally tipped
with two dark-brown dots. Ventral spine slender, reaching upon
the hind coxae.

Distribution. Canada, Massachusetts, New York, Penn-
sylvania, Maryland, Virginia, Wisconsin, Illinois, Nebraska,
Kansas, Iowa, Missouri, Colorado, Indian Territory, Texas
California. This species is stated to occur generally through-
out the south and west ; it is rare in Massachusetts.

Habits.

Podisus spinosus has been frequently confounded with
P. serieventris in the collections I have examined, and in

134 THE GYPSY MOTH APPENDIX.

some series the two species closely approach each other.
P. spinosus usually reaches a size not attained by sen'evenln'x.
In the latter species the antennae are generally spread over
with brown and the humeral angles are bluntly acute, not
produced into slender spines. In spinosus there is usually a
well-defined sinuation in rear of each spine.

The life history of this species, as briefly given by Riley,
is as follows :

The eggs of P. spinosus ... are bronze-colored, caldron-
shaped objects, with a convex lid, around which radiate fifteen or
sixteen white spines. They are attached side by side, in clusters
of a dozen or more, to leaves and other objects. . . . The young
bug is ovoid, shiny black, with some bright crimson about the
abdomen. In the full-grown larva . . . four yellowish spots
appear on the thorax, and the abdomen becomes more yellowish.
In the so-called pupa, distinguished by wing-pads, the ochre yellow
extends still more, and in the perfect insect the black entirely dis-
appears. In the immature stages the shoulders are rounded, not
pointed ; the antennae are four-jointed instead of five-jointed as
in the adult, and the feet or tarsi have but two joints instead of
three.

The diet of the young seems to be principally vegetarian, but
we have mentioned elsewhere (Fourth Rep. Ins. Mo., p. 20)
instances where the larva has been seen to destroy larvge of the
Colorado Potato beetle four or five times its own size. (Fourth
Rep. U. S. Eut. Com., p. 98.)

At the time the Colorado potato beetle was spreading east-
ward, P. spinosus was perhaps its most frequently observed
insect enemy, as is shown by its frequent mention in articles
on the subject appearing at that time, and its services in
destroying this beetle were of sufficient value to call out
the commendation of many entomologists. In destroying
the cotton worm (Alelia argillacea) Riley rates this bug as
" the most abundant and effective " of the Heteroptera known
to attack the insect. The full list of insects which P. spinosus
is known to attack is given below :

Diapheromera femorata Say (Riley, Rep. U. S. Dep. Agr.,
1878, p. 245), Coccinella sp. ? (Walsh, Amer. Ent., 1869,
vol. I., p. 13), Crioceris asparagi Linn. (Chittenden, Year
Book U. S. Dep. Agr., 1896, p. 346), Doryphora decem-

PREDACEOUS BUGS. 135

lineaia Say (Glover, Rep. U. S. Dep. Agr., 1866, p. 43, and
many other writers), Galerucella luteola Mull (Riley, Rep.
U. S. Dep. Agr., 1892, p. 167), Pier is rapce Linn. (Murt-
feldt, Rep. U. S. Dep. Agr., 1884, p. 417), Ht/pliantrin c tinea
Drury (Walsh, Amer. Ent., vol. I., 1869, p. 59), Orgyia
leucostigma S. and A. (Howard, Bull. 5, Tech. Ser., 1897,
p. S), Carneades scandens Riley (Riley, First Rep. Ins. Mo.,
1869, p. 77), Aletia argillacea Hhn. (Comstock, Rep. U. S.
Dep. Agr., 1879, p. 289), Caccecia fervidana Clem. (Pack-
ard, Fifth Rep. U. S. Ent. Com., 1890, p. 194), Carpocap*<i
pomonella Linn. (Le Baron, 3d, Rep Ins. 111., 1873, p. 184),
Gymnonychus appendiculatus Hartig (Glover, Rep. U. S.
Dep. Agr., 1875, p. 118), Selandria barda Say (Osborn,
Can. Ent., 1884, p. 151).

Telenomus podisi Ashm. (Ashmead, Proctotrypidre, 1893,
p. 159) and Trissolcus podisi Ashm. (ibid., p. 163) have been
reared from the eggs of P. spinosus.

PODISUS ACUTISSIMUS Stal. (Plate 1, fig. 5.)

1870, Podisus (Tylospilus) acutissimus Stal, Enum. Heniipt.,

part L, p. 53.
1875, Tylospilus acutissimus Uhler, Bull. 5, vol. I., IT. S. Geol.

Surv. Terr., p. 283.
1880, Podisus acutissiimis Distant, Biol. Cent. Am. Rhync., vol.

I., pp. 40, 41, pi. II., fig. 22.
1895, Podisus acutissimus Gillette-Baker, Bull. 31, Col. Agrl.

Expt. Station, Heniipt. Col., p. 12.

Length, 9 mm. Very pale olive yellow, heavily punctate with
dark brown on posterior part of pronotum and lower part of
scutellum. Head somewhat narrowed anteriorly. Tylus longer
than lateral lobes, which are obliquely rounded and margined
with dark brown at their outer ends. Between the dark-brown
eyes and extending backward to the pronotum are two longi-
tudinal dark-brown markings. First segment of antennae small,
scarcely projecting beyond the lateral margin of head, pale yel-
low, darkened outwardly ; second segment of antennae slender,
dark brown ; third segment three-fourths as long as second, red-
dish yellow, dark brown at base ; fourth segment as long as third,
testaceous ; fifth segment two-thirds as long as fourth, testaceous,
darker toward the apex. Rostrum slender, reaching upon middle
coxae ; the second segment scarcely reaching the fore coxae, pale
amber colored.

136 THE GYPSY MOTH APPENDIX.

Prouotum with an irregular ivory-yellow callous on the dorsuni
anteriorly ; lateral margins with fine granular teeth. Humeral
angles very acute, terminating in slender spines which project an-
teriorly. A well-marked baud of dark-brown punctures extends
across the prouotum between the humeral angles, darkening to
black at the posterior margin. Post-humeral margins oblique and
curved.

There is a large ivory-yellow bald spot in each basal angle of the
scutellum, flanked outwardly by a minute brown callous and in-
wardly by scattering brown punctures which extend in a band
across the scutellum. Behind these spots and separated from
them by a pale olive-yellow band is a well-defined dark-brown V-
shaped marking, posterior to which at the tip of the scutellum
there is an ivory-yellow crescent-shaped marking.

Corium pale olive yellow, with a black dot outwardly nearly
opposite the apex of the V-shaped marking. Membrane glassy,
with a large dark-brown marking. Conuexivum olive yellow,
without dark markings. Uuder-surface without conspicuous mark-
ings, pale amber colored anteriorly, darkening to olive yellow
posteriorly. Ventral spine very long, reaching middle coxse.
Legs amber colored ; tarsi pale browu.

Prof. Carl Baker of Auburn, Ala., has very kindly sent
me a specimen of P. acutissimus from Texas. This species
is the most conspicuously colored of any that I have ex-
amined, and may be recognized by the V-shaped marking
and bald spots on the scutellum, the transverse brown band
and sharp, curved spines of the pronotuui, the vitta of the
membrane and the long ventral spine.

Distant has figured a specimen having a bald spot at the
middle of the base of the scutellum (Biol. Cent. Arner.
Rhync., pi. II., fig. 22). This specimen, which he states is
a typical one, is in the Stockholm Museum. The specimen
which I have examined lacks this marking, and it is presum-
ably a variable character. The rostrum is more slender than
that of any of our northern species, but is sufficiently stout
to indicate predatory habits on the part of the species.

Distribution. Colorado, Texas, Mexico, Guatemala.

PREDACEOUS BUGS. 137

PODISUS MUCRONATUS Uhler. (Plate 1, fig. 9.)
1897, Podisus mucronatus Uhler, Trans. Md. Acad. Sc., pp. 386, 387.

Length, 9 mm. Head rounded anteriorly, the lateral lobes not
extending beyond tylus. General color testaceous, with dark-
brown punctures arranged in longitudinal series. First segment
of auteunje projecting slightly beyond the lateral margin of head ;
second segment pale amber colored, slender, two-thirds as long
as head ; third segment two-thirds as long as second, darkened
toward apex ; fourth and fifth segments of nearly equal length, pale
brown, each three-fourths as long as second. Rostrum of medium
size, reaching to hind COXJB. Pronotum ivory yellow, sparingly
punctate with brown, and bordered on its anterior lateral margins
with pale yellow. Humeral angles produced into slender dark-
brown spines, which curve sharply toward the head. Scutellum
ivory yellow, very sparsely punctate with brown, and with a large
bald spot at the tip and a smaller bald spot in each basal angle.
Coriuni sanguineous, thinly punctate with brown. Membrane
dark bronze colored. Under-surface sulphur yellow, tinged later-
ally with reddish, with scattering pale-brown punctures anteriorly.
Ventral spine slender, acute, reaching upon hind coxae. Legs
pale amber colored.

Distribution. Florida, Cuba.

Prof. P. R. Uhler, to whom I am indebted for many
favors in connection with the preparation of this paper, has
very kindly given me an opportunity to examine this inter-
esting species.

138 THE GYPSY MOTH APPENDIX.

Explanation of Plate 1.

Figures of insects drawn by J. H. EMERTON ; structural details by

A. H. KlKKLAXD.

Fig. 1. Podisus placidus, natural size.

Fig. la. Podisus placidus, right humeral angle enlarged.

Fig. 16. Podisus placidus, anterior margin of head enlarged.

Fig. 2. Podisus serieventris, natural size.

Fig. la. Podisus serieventris, right humeral angle enlarged.

Fig. 1b. Podisus serieventris, ventral spine enlarged.

Fig. 3. Podisus crocatus, natural size.

Fig. 3a. Podisus crocatus, right humeral angle enlarged.

Fig. 4. Podisus spinosus, natural size.

Fig. 4a. Podisus spinosus, right humeral angle enlarged.

Fig. 5. Podisus acutissimus, natural size (from Distant).

Fig. 5a. Podisus acutissimus, right humeral angle enlarged.

Fig. 6. Podisus gillettei, natural size.

Fig. 6a. PodiSUS gillettei, ventral spine enlarged.

Fig. 66. PodiSUS gillettei, right humeral angle enlarged.

Fig. 7. Podisus cynicus, natural size.

Fig. "a. Podisus cynicus, ventral spine enlarged.

Fig. 76. PodiSUS cynicus, anterior margin of head enlarged.

Fig. 7c. Podisus cynicus, right humeral angle enlarged.

Fig. 8. Podisus mucronatus, natural size.

Fig. S. Podisus mucronatus, right humeral angle enlarged.

Fig. 9. Podisus modestus, natural size.

Fig. 9a. PodiSUS modestus, ventral spine enlarged.

Fig. 96. Podisus modestus, right humeral angle enlarged.

Plate I.

to.

"S3

71

"