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BULLETIN..OF THE

USDEPARIMENT OFAQRICULTURE © 2

No. 204

May 21, 1915.

REPORT ON THE GIPSY MOTH WORK IN NEW
ENGLAND.' |

By A. F. Burgess,
In Charge of Gipsy Meth and Brown-Tail Moth Work.

INTRODUCTION.

On March 1, 1913, the gipsy-moth work conducted by the Bureau
of Entomology, U. S. Department of Agriculture, was reorgan-
ized, and the writer was placed in charge under the direction of the
chief of the bureau. ©

The obiect of this Federal work is to use every measure possible
to prevent the spread of the gipsy moth and the brown-tail moth?
to uninfested parts of the United States.

The main office, which is maintained at 43 Tremont Street, Bos-
ton, Mass., furnishes quarters for the men in charge of the main
projects and the necessary clerical force. The Gipsy Moth Labora-
tory, which serves as headquarters for the experimental work, is
located at Melrose Highlands, Mass., although one branch of this
work is conducted at the Bussey Institution at Forest Hills, Mass.
During the past two years a summer laboratory has been main-
tained for special experiments at Worcester, Mass. A storehouse is
located at Melrose Highlands, Mass., where the necessary tools and
equipment are stored and repaired.

The work is divided into two distinct lines: (1) Field work, con-
sisting of scouting, and applying hand methods for controlling these

~ insects, as well as a thorough inspection of the plant products shipped

from the infested area, and (2) experimental work, which includes
the introduction of parasites and natural enemies, together with care-

ful studies of the food plants and other factors, in order to devise

more efficient and effective methods of control, as well as an investi-
gation of the relation of silviculture to the gipsy-moth problem. <A

1 This publication is prepared to show the different lines of work which are being taken up and the
results that have been secured.

2 The life history, habits, and methods for controlling these insects have been published in Farmers’
Bulletin 564, U. S. Department of Agriculture.

82942°—Bull. 204—15——1

2 BULLETIN 204, U. 8S. DEPARTMENT OF AGRICULTURE.
general outline of the problems and investigations and the differ-
ent activities of the work has already been published! in the Journal
of Economic Entomology.

During the fiscal year which ended June 30, 1914, an average of
275 men was employed. The greater number were engaged in
field operations, but a force of approximately 40 men were employed ©
on different phases of experimental projects. 2

EXPERIMENTAL WORK.

In carrying on measures for the control of any insect pest it is
necessary to conduct many experiments in order to determine the
means which are most feasible for reducing the damage. For more
than 20 years experiments have been carried on more or less con-
tinuously by the State of Massachusetts and other States to which
the gipsy moth has spread, as well as by the Bureau of Entomology,
for the purpose of perfecting field measures for holding the insect in
check, and from time to time improvements have been made which
have reduced the cost of handling infested areas. Spraying ma-
chinery has been developed so that at the present time it is entirely
practical to treat large areas at a moderate cost. The banding of
trees with tanglefoot has largely replaced the use of burlap bands
and reduced the cost of this method of treatment. In fact, so much
work has been done along these lines that the best methods of treat-
ment are well understood and practiced in the areas where the gipsy
moth is prevalent. Minor improvements are being made from time
to time but in general satisfactory methods of hand suppression
have been adopted.

In 1905, when the Federal gipsy-moth work was being organized, it
was considered very necessary and desirable to introduce the parasites
and natural enemies which occur in foreign countries of both the
gipsy moth (Porthetria dispar L.) (Pl. I) and the brown-tail moth
(Euproctis chrysorrhoea L.) (Pl. Il). The idea was prevalent that
by securing and liberating these natural checks on the increase of
these species, it would be possible greatly to reduce the damage, and
it was hoped that the parasites would bring the pests as well under
control as is the case in Europe. Accordingly arrangements were
made by Dr. L. O. Howard, Chief of the Bureau of Entomology, for
the collection of a large amount of parasitic material in various
European countries, and later similar arrangements were made with
entomologists in Japan. This work was carried on for the first five
years in cooperation with the State of Massachusetts. Several agents
of the Bureau of Entomology have been sent to Europe on different.
occasions to investigate conditions and forward to this country as
large an amount of parasitized material as could be collected. For
two seasons this work was conducted by Mr. W. F. Fiske, who was
assisted in the summer of 1912 by Mr. L. H. Worthley. Various

1 Jour. Econ. Ent., v. 7, No. 1, p. 83-87, Feb., 1914.

GIPSY MOTH WORK IN NEW ENGLAND. 8

assistants and collectors were engaged to obtain parasitized material
which was forwarded to the Gipsy Moth Laboratory at Melrose
Highlands, Mass. After the completion of the foreign work in 1912,
it appeared that not only were the parasites, and a contagious dis-
ease known as the ‘‘wilt,’’ prime factors in controlling the gipsy
moth in Europe, but in addition to these a pronounced obstacle to
the increase of the pest arose from the fact that forest conditions,
particularly in Germany, furnished in the main unfavorable food for
the caterpillars. The observations indicated that this factor, in
addition to the natural enemies already mentioned, was responsible
for rendering the gipsy moth of slight importance to forest growth
except at periodic intervals.

In 1912 anumber of areas were under observation by Mr. Worthley
in the forests of Germany, and at that time the infestation was severe.
Deciduous trees in these areas were defoliated and in some cases
many trees completely denuded of foliage. Similar studies were
made by Mr. Fiske in Italy, where a few infestations were found
which were more serious, if possible, than those observed in the Ger-
man forests. During the summer of 1913 no agent of the bureau
was engaged in making foreign observations on the gipsy moth. It
seemed best in the spring of 1914 to have the areas in Germany
revisited for the purpose of determining the result of the previous
infestations and to secure data on the increase or the decrease of the
species. Accordingly, early in the spring of that year, Dr. John N.
Summers, who for a number of years had been in general charge of
the parasite work at the Melrose Highlands Laboratory, was detailed
to visit the areas mentioned and to secure all the data possible on the
fluctuations of the gipsy moth, as well as to obtain parasitic material
for shipment to this country, in case it could be found in collectible
quantities. The result of this work has been reported by Dr. Sum-
mers, and it appears that in no place in Germany where the insect
was reported in 1912 was there a severe or even moderate infestation
in 1914. It was impossible, therefore, to obtain parasitized material,
and in most cases the insect was so rare that little data beyond the
mere fact that it still existed in the areas could be secured.

About the middle of June a report was received that a heavy infes-
tation of the gipsy moth occurred in the Province of Bereg, Hungary.
This information was received from Dr. Josef Jablonowski, and Dr.
Summers was instructed to take up his investigations in that region.
_ Unfortunately it was impossible for him to arrive in the infested
forest until after the feeding of the caterpillars was finished and most
of the eggs for the new brood of moths had been laid. Parasites were
not present to any marked extent at this time, which was not sur-
prising, owing to the fact that the observations were made too late
in the season. Some evidence was secured that the wilt disease was
present in the area, but a fairly good increase of the species was noted
except at points where the trees had been completely denuded and
where the caterpillars had died from starvation or had moved to

‘ : a Cs ~ de, A
4 BULLETIN 204, I Ss DEPARTMENT OF AGRICULTURE, - ais ie Os

adjoining tree erowth in search of food. Dr. Summers eviek that
not less than 5,000 acres were almost completely defoliated in the ©
forests in Hungary where he made his observations. The growth
consisted entirely of hardwoods; the oak predominating, and a |
species of Carpinus, beech, and maple occurring in the order men-
tioned. A few elm trees were also present.

The results of the European investigations carried on during the
past few years, aside from furnishing a good supply of parasitic
species, has proved beyond question that as far as the forests are
concerned the character of the growth is of prime importance from
a gipsy-moth point of view. Coniferous forests predominate in Ger-
many, and these are not injured by the gipsy moth. The deciduous

forests in that country are not large, and the injury is periodical and |

severe. In Hungary large deciduous forests are present and the
infestation is more or less common from year to year. Severe defolia-
tion usually continues for about three years before a marked decrease
of the moth is observ , and then a few years pass before another
outbreak is noticed. 1 his information, with certain data which have
been collected in this country for the past few years relative to the
increase or decrease of the gipsy moth under New England forest con-_
ditions, together with a careful study of the feeding habits of the
gipsy-moth caterpill lar in all its stages on the various species of tree
growth, and the beneficial influence which is bemg felt to a greater
extent each year as a result of the increase of ‘the parasites and
natural enemies of the moth and the severity of the wilt disease, all
point the way to more effective methods of handling the gipsy-miotn
problem.

The different phases of the experimental work, as it is being carried
on, will be touched upon briefly in order to indicate the changed con-
ditions which are being brought about in the infested area in | New
England.

PARASITE WORK.

As has already been stated, the first attempts to introduce the
parasites and natural enemies of the gipsy moth and brown-tail moth
were begun in 1905. In all more than 30 enemies of these insects,
which are present to a greater or less extent in their native homes,
have been introduced into New England. More than half of the ~
species have been received in sufficient numbers so that colonies |
could be liberated under field conditions, and they have had an —
opportunity to demonstrate their ability to withstand climatic con- ~
ditions and to become established in this country. As should be ~
expected, a large number of the species have failed to survive. A
few have been recovered from year to year, showing that while they
have the ability to maintain themselves, they have not yet been —
able to increase to a sufficient extent to become a useful factor in
controlling their hosts. A few species have become established and ~
are increasing satisfactorily. In fact, some of them are making sufh- —
cient headway so that they have already become a very appreciable —

Bul. 204, U. S. Dept. of Agriculture. PLATE l.

Joo wagers pis: :

THE GIPSY MOTH (PORTHETRIA DISPAR).

Upper left, male moth with wings folded; just below this, female moth with wings spread ;
just below this, male moth with wings spread; lower left, female moth, enlarged; top
center, male pupa at left, female pupa at right; center, larva; on branch, at top, newly
formed pupa; on branch; just below this, larva ready to pupate; on branch, left side,
pup; on branch, center, egg cluster, on branch, at bottom, female moth depositing egg
cluster. All slightly reduced except figure at lower left. (From Howard and Fiske.)

Bul. 204, U. S. Dept. of Agriculture.

PLATE |.

THE BROWN-TAIL MOTH (EUPROCTIS CHRYSORRHOEA).

Upper left, hibernating web; just below this, small larve feeding at left, larger larva at right;
just below this, female moth depositing eggs at left, egg mass at right; lower left, egg mass
with eggs exposed ; top center, male pupa at leit, female pupa at right; upper right. cocoon
ineased in leaves; lower right, male moth above, female moth below. All slightly reduced.
(From Howard and Fiske.)

eee *

GIPSY MOTH WORK IN NEW ENGLAND. 5

factor in reducing the infestation of the gipsy moth even under our
adverse food-plant conditions. The most valuable species will be
mentioned briefly in order to give an idea of their habits.

:

Fie. 1.—Anasiaius bifasciatus: Adult female. Greatly enlarged. (From Howard.)

Two species of minute hymenopterous parasites which attack the
eggs of the gipsy moth have become established in New England.
One, Anastatus bifasciatus Fonsc. (fig. 1), occurs in Europe and
Japan, and although only one brood of this insect is reproduced each

Fig. 2.—Schedius kuvanae: Adult female. Greatly enlarged. (From Howard.)
season, it has succeeded in maintaining itself and increasing in prac-
tically every locality in which it has been liberated. The other

species, Schedius kuvanae How. (fig. 2), was imported from Japan.

6 BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE.

A brood of this species develops under favorable weather conditions
‘in about four weeks. The first brood appears in August and the
insect continues to breed until cold weather sets in. Owing to the
fact that several broods develop in a single season, the insect increases
very rapidly. It can be reared in the laboratory for the purpose of
colonization, and this work is bemg done each year. Unfortunately
the insect does not always survive the winter in good condition, so
that its occurrence in the colonies where it is liberated is by no means
as uniform as that of Anastatus. |

Apanteles lactevcolor Vier. (fig. 3) is a small hymenopterous parasite
which deposits its eggs in the small caterpillars of the brown-tail
moth in August. The eggs of the parasite hatch in the body of the
small caterpillar, but development is very slow during the fall.
Caterpillars that are attacked in
this way feed and enter the hiber-
nating web with their more for-
tunate comrades. They pass the
winter and emerge with the others
early in the sprmg. As soon as
they have become active and
begin feeding the Apanteles larva
also begins feeding and by the
time the caterpillar is about one-
fourth of an inch long this inter-
nal parasite has become large
enough to destroy it. The Apan-
teles larva then makes its way ~
from the body of the caterpillar,
forms a cocoon (Pl. III, fig. 1),
and early in June the adult para-
site emerges. ‘This is the time of
year when small caterpillars of the gipsy moth are feeding, and the
parasites attack these caterpillars and pass through one generation
with the gipsy moth as a host.

Another species which attacks both the gipsy and brown-tail
moth caterpillars is a parasitic fly known as Compsilura concinnata
Meig. (Pl. III, fig. 2). This insect is about the size of the house
fly, although its habits are strictly those of a caterpillar parasite.
Karly in the spring the female fly deposits a small maggot in the
body of the larva of the brown-tail moth which feeds inside the .
body of the caterpillar and becomes full-grown early in June. At
this time the maggot burrows through the epidermis of the host
and forms a puparium from which, in about a week, the adult fly
emerges. This brood attacks the gipsy-moth caterpillars, the adult

Fig. 3.—A panteles lacteicolor; Adult female and co-
coon. Muchenlarged. (Original.)

GIPSY MOTH WORK IN NEW ENGLAND. Fi

flies emerging early in July. One or more broods may follow
before cold weather in case native larve are at hand to serve as
hosts.

A species of Apanteles (A. melanoscelis Ratz.), which was received
in small numbers from Italy in the summer of 1912, was liberated
near the laboratory at Melrose Highlands, Mass. Itis double-brooded,
both generations being passed on. gipsy-moth caterpillars. This
species has maintained itself since its introduction and promises to
be a most valuable addition to the enemies of the gipsy moth. It
has not been imported or recovered in sufficient numbers from the
colony liberated in this country so that other colonies could be
established, but is considered a very valuable species.

The Calosoma beetle (C. sycophanta L.) (Pl. IV), while not strictly
a parasite, is at the present time doing more effective work against
the gipsy moth than any single introduced species. This large
green beetle hibernates in the ground during the winter and emerges
about the first of June. It feeds on the caterpillars and pupez of
the gipsy moth and brown-tail moth, as well as on such native spe-
cies as it may find. These beetles climb trees and are continuously
searching for food. They live two or three years and after mid-
summer burrow into the ground where they remain during the winter.
On the average, 100 eggs are deposited in the ground annually by
each female. The beetle larve hatch in about a week. They are
proficient tree climbers and feed constantly on the caterpillars and
_ pupe of the gipsy moth or other insects until they become full grown
about the middle of July. This species has increased and spread
in a most satisfactory manner, and has made great inroads on the
gipsy moth in many localities. Both the beetles and the larve attack
the caterpillars of the brown-tail moth, so that double benefit results.

Another parasite, one which attacks the brown-tail moth only,
is a hymenopteron known as WMeteorus versicolor Wesm. It has
become well established, but is seldom found in great numbers.
It is possible that this species may increase rapidly later on, but
at the present time it does not appear to be as beneficial as those
that have previously been mentioned. Several species of introduced
tachinid flies are recovered occasionally, but in such small numbers
as to indicate that they are not at the present time doing effective
work.

An enormous amount of careful study and a large number of
detailed experiments have been carried on in order to determine the
life histories, habits, and utility of the different species which have
~ been introduced. It has been necessary from time to time to develop
new methods of handling these species in order to get the data
desired, and practically all the equipment and breeding devices

8 BULLETIN 204, Wes. DEPARTMENT OF AGRICULTURE.

used at the laboratory are of original desion and have been constaictedis

for the purpose of furthering the gipsy-moth investigations. Much* |
valuable information of a biological nature has been secured which —

is not only of direct value to the parasite phase of the gipsy-moth
work but has been found useful in connection with insect problems
in various parts of the country.

»

RECENT COLONIZATIONS AND RECOVERY OF IMPORTED PARASITES,

During the past two or three years careful investigations have |

been carried on to determine the increase and spread of the different
parasites. In the summer of 1914 this work was in charge of Mr.

S. S. Crossman. As large a number as possible of the different |

species have been liberated in the remote parts of the infested area

for the purpose of securing the establishment of these valuable —

species over the entire territory at the earliest possible date. In
the fall of 1913 Anastatus bifasciatus was recovered from 41 towns
and the parasitism in the collections secured averaged about 30
per cent. From one collection over 43 per cent of the eggs had been
destroyed by this insect. As a result of the collection made during
the winter, 1,561 colonies of this species, totaling 1,561,000 speci-
mens, were liberated; 1,047 of the colonies were placed in 12 towns
in Massachusetts and 514 in three towns in New Hampshire. This
insect spreads very slowly, hence it is necessary to liberate many

colonies. The plan which is being used is to place a sufficient num-’

ber of colonies in a town so that no further colonization in that town
will be necessary. ‘The work on this insect required the collection
in the fall of 1913 of about 7,500 gipsy-moth egg clusters and these
were secured from over 100 selected localities.

In the fall of 1913, 33 towns were colonized with Schedius kuvanae.
The number of colonies placed in a town varied from 1 to 10, depend-

ing on the gipsy-moth infestations. Most of the colonies were liber- |

ated in the southern part of the infested territory in Massachusetts,
as it was believed that this section would be favorable for the survival
of the species during the winter. Jn all 110 colonies were liberated,
containing over 375,000 individuals. This species spreads more
rapidly than Anastatus, so itis not necessary to place as many
colonies in a given area. Over 14,000 gipsy-moth egg clusters were
collected from about 100 selected localities within the area bounded
by Exeter, N. H., and Berlin, Bolton, and Mashpee, Mass. This
material was used at the laboratory to secure records of the percentage
of parasitism in colonies that had been liberated in previous years.
The spring of 1913 was very favorable for Apanteles lacteicolor, and
it was recovered from 69 towns. This was the result of collections
of 92,000 brown-tail moth webs, a supply coming from every one of

Bul. 204, U. S. Dept. of Agriculture. PLATE III.

Fia@. 1.—COCOONS OF APANTELES LACTEICOLOR IN MOLTING WEB OF THE BROWN-TAIL
MOTH. (ORIGINAL.)

FiG. 2.—THE COMPSILURA FLY (COMPSILURA CONCINNATA): ADULT FLY, MucH EN-
LARGED, AT LEFT; PUPARIA, ENLARGED, AT RIGHT. (ORIGINAL.)

Bul. 204, U. S. Dept. of Agriculture. PLATE IV.

THE CALOSOMA BEETLE (CALOSOMA SYCOPHANTA).

Upper left, eggs; lower left, adult beetle feeding on gipsy moth caterpillar; upper right, gipsy
moth pups destroyed by Calosoma lary; center,Calosoma larva, ventral view; right center,
Calosoma larva, dorsal view; lower right, Calosoma pupa in cavity in ground. (From Howard
and Fiske.)

—, °
és

Pp.

Bei F
ao

om

MAP SHOWING DISPERSION

APANTELES LACTEICOLOR

NEW ENGLAND
1914

eee) Towns from which recoveries have been made

|

PRT RT a

MAP SHOWING DISPERSION
COMPSILURA CONCINNATA

NEW ENGLAND
1914
a Towns from which recoveries have been made

@ Towns where colonies were liberated in 1914

GIPSY MOTH WORK IN NEW ENGLAND. 9

the New England States. Fifty-six colonies were liberated in 48
towns, a total of over 76,000 cocoons being placed in the field. During
the winter of 1913-14 collections of brown-tail moth webs were made
in 72 towns scattered over the infested area in New England. The
recovery of the parasite indicates that it has become established as
far north as Monson, Me.; west as far as North Adams, Mass.; and
south as far as Waterford, Conn. About 2,500 cocoons were liber-
ated in the spring of 1914 in three of the Connecticut Valley towns
in Vermont. Our work on this species was supplemented by cooper-
ative work which was carried on by Prof. W. C. O’Kane, State ento-
mologist of New Hampshire. From collections made by his assistants
he was able to colonize Apanteles in 11 towns, 1,000 specimens being
put in most of these colonies. Similar work is carried on in coopera-
tion with the gipsy-moth laboratory by Maj. E. E. Philbrook, State
moth superintendent of Maine, but a definite statement of the num-
ber of colonies liberated can not be given at this time. An arrange-
ment was made during the fall of 1913 to continue cooperative
parasite work between the laboratory and the entomologist of the
Dominion of Canada, Dr. C. Gordon Hewitt. In the spring of
1914 he detailed one of his assistants, Mr. L. S. McLaine, to take up
work in Massachusetts, using the gipsy moth laboratory as head-
quarters. Mr. McLaine secured several assistants, and as a result of
his efforts about 1,000 Apanteles cocoons were sent to the brown-tail
moth infested area in New Brunswick for the purpose of colonizing
the species. Similar efforts were made the previous year and colonies
were liberated in New Brunswick and Nova Scotia, and in several of
these places the species survived the winter of 1913. (Pl. V.) . In
general it should be said that the winter of 1913-14 resulted in a
marked decrease in the abundance of Apanteles. An unusually
high mortality of caterpillars in the brown-tail webs accounts for this
decrease. The exact cause of the mortality of the brown-tail moth
caterpillars can not be definitely stated, but it seems to be attributable
to an unusually severe winter, the presence to a greater or less extent
of internal parasites in the caterpillars, and the effects of the brown-
tail fungus, a disease which also affects the larve of this species.

The parasitism of the gipsy moth by Apanteles lacteicolor was not
nearly as high in 1914 as during the previous year, and was of course
a direct result of the failure of the brown-tail moth caterpillars to
bring through the first generation of the parasite.

During the summer of 1913 Compsilura concinnata was recovered
from 54 new towns. Eleven of these were in Maine, 14 in New
Hampshire, and 29 in Massachusetts. In the summer of 1914 this
_ insect was found in 44 new towns—2 in Maine, 21 in New Hampshire,
20 in Massachusetts, and 1 in Rhode Island. It is possible that

82942°—Bull. 204—15——2

10 BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE.

Compsilura is present in more localities in Maine, but we have been _

unable to secure definite records to that effect. The following table
is interesting, as it shows the general rate of dispersion of this para-
site. The spread recorded is based on distance from Melrose High-
lands, Mass., and is mostly due to natural spread, although a few
small colonies have been lberated outside of the area where the
species was known to occur in 1913. :

Taste I.—Dispersion of Compsilura concinnata. Distance recovered from Melrose
Highlands, Mass.

} 1913 1914

From Melrose Highlands: | Miles. Miles.
IN Gries 2 8S Aa TR Te 73 100
Northeast: 2 sc: a 100 130
SOUL eee eee ees 50 50
South WeSh_. sc 2 ae eesee 40 55
Wiestiy tea! 52a. fee 50 65
Northwest —. -.-. 8.2.2... 7 80

It is undoubtedly true that this species 1s now present over an
area which would be represented by connecting the points indicated
by the directions and distances given in the table for 1914. (PI. VI.)
Four thousand five hundred and sixty-five Compsilura were liber-
ated in 10 new towns in 1913 and 10,000 were placed in 21 new
towns in 1914, as follows: Eight in New Hampshire, 5 in Vermont,
2 in Massachusetts, 2 in Rhode Island, 3 in Connecticut, and 1 colony
was forwarded to a substation of the Bureau of Entomology at
Koehler, N. Mex., in order to test the value of this species as an
enemy of the range caterpillar (Hemileuca oliviae Ckll.), an insect
which is causing enormous damage to the grazing lands in that State.
In addition to the number of specimens of this species colonized in
1914, about 5,000 were secured by Mr. McLaine and shipped to New
Brunswick; about 3,000 were secured by Mr. R. S. Ferguson, assist-
ant in the moth department of the State of Maine, who, with several
assistants, were collecting for the purpose of establishing colonies in
that State, and over 2,500 were collected and colonized by Prof.
O’Kane’s assistants in New Hampshire.

Three hundred and sixty-five sample collections of gipsy-moth
larvee which were secured during the summer of 1914 from scattered .
localities in Maine, New Hampshire, Massachusetts, and Rhode
Island, consisted of over 99,000 caterpillars. This material required
the use of over 500 rearing trays at the laboratory and the constant
attention of several assistants to feed the larve in each tray and
record the parasitism, mortality, and other data.

Based on 25 collections of gipsy-moth larve taken at widely scat-
tered points in the gipsy-moth-infested area and aggregating 46,000

GIPSY MOTH WORK IN NEW ENGLAND. "uf

specimens, an average of 20 per cent of parasitism by Compsilura
was found to exist. Several large single colonies showed a degree
of parasitism ranging from 40 to 50 per cent. The results secured
with this species during the summer of 1914, based on the number of
parasites obtained from the collections, indicate that the distribution
of this insect is more likely to be local than general, since in areas
where it was abundant in the summer of 1913 it was recovered in
very small numbers in 1914, in spite of the fact that a moderate
infestation was present during the latter year.

Apanteles melanoscelis, a species already referred to, is showing
considerable promise. As high as 19 per cent of the second stage
gipsy moth larve collected at Melrose Highlands during the summer
of 1914 were parasitized. This species was recovered from two new
towns this year, namely, Stoneham and Saugus.

Considerable additional data have been secured from other imported
parasites which have been colonized in this country and have sur-
vived in more or less numbers. The details are not given, however,
inasmuch as it has not been demonstrated thus far that they are of
particular value as parasites of either the gipsy moth or the brown-tail
moth. |

Pieromalus egregius Forst. has been recovered in small numbers
from many parts of the territory infested by the brown-tail moth.
The larva of this insect works as an external parasite of the small
brown-tail moth caterpillars in the webs. Monodontomerus aereus
Walk., a parasite of gipsy and brown-tail moth pups, is known to
occur throughout most of the area infested by these insects. It has
been reared in small numbers from tachinid puparia and undoubt-
edly has other unrecorded hosts.

Calosoma sycophanta has been found during the summer of 1914
over a much wider area than that previously recorded (Pl. VII).
Owing to the ease with which the beetles and their larve could be
collected in the field it has been possible to liberate 37 colonies in
New Hampshire, Massachusetts, Rhode Island, and Connecticut.
These were placed outside the area where the species was previously
known to occur. In addition, colonies of Calosoma have been liber-
ated in Maine and New Hampshire by State officials. Colonies have
been liberated in New Brunswick, Nova Scotia, and Quebec as a
result of collections made by Mr. McLaine and his assistants, and
1,700 specimens were collected by Mr. H. E. Smith and forwarded
to Koehler, N. Mex., to test their value as an enemy of the range
caterpillar.!

1 This work was carried on by arrangement with Mr. F. M. Webster, who is in charge of the Cereal
and Forage Crop Insect Investigations of the Bureau of Entomology.

ES ee Ne Ee ee ae ae ae ee en

12 - BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE.

As aresult of the Calosoma scouting work carried on during July
and August, 1914, it has been found that this species exists in 18 towns
in Maine, 93 in New Hampshire, 1701n Massachusetts, 3in Rhode Island, |
and 2in Connecticut. Data concerning this insect obtained during the
present year indicate that the species is able to maintain itself in con-
siderable numbers in areas where the gipsy-moth infestation is slight
and that as a rule the species continues to be abundant after it once
becomes established in a locality. Owing to the well-known habits
of the beetles in migrating considerable distances, it was thought
that territory with light infestation would be deserted in favor of
areas where caterpillars occurred in abundance. This does not prove
to be the case and it is another feature which increases the value of
this beneficial insect.

The table below shows the colonization of the principal parasites
during 1913 and 1914:

TaBLe I1.—Colonization of natural enemies in 1913 and 1914.

|
| Number of colonies | Number of individuals | Towns where colo-

liberated. liberated. nies were placed.
Species. | ps ae Ee ee :
1913 | 1914 1913 1914 1913 1914

Gee pees irc" eras ace
Anastatus bifasciatus!...............- 1, 500 | 1,561 | 1,500,000 | 1,561,000 242 15
Sehedags kuvanae 222-222 eo ee | 110 502 352,000 | 2,083,254 33 iil
Apanteles lactercolor 1--~ 2.2. --4-2.52- 56 14 76, 000 13, 119 48 14
Compsilura concinnata )_............- 10 28 4, 565 23, 638 10 26
Calosoma sycophanta! ........2..-..- | 45 49 | 6,175 8, 104 42 38

1 A part of the collections and colonization were made by cooperative arrangements with the State officials
of Maine and New Hampshire, with the Dominion Entomologist of Canada, and with Mr. F. M. Webster
of this bureau.

2 In many of these towns only a few colonies were liberated.

The results of the work accomplished by introduced parasites of
the gipsy moth during the past year have been excellent. It is true
that the increase of Apanteles lacteicolor has been seriously retarded
but the other species have given a good account of themselves. The.
fact that Compsilura and Calosoma are becoming established in the
remote parts of the area infested with the gipsy moth and are able
to maintain themselves under these conditions is very encouraging,
as the work of these species will tend to reduce the infestation and
be an important factor in preventing the spread along the outside
border. ;

WILT-DISEASE INVESTIGATIONS.

In connection with the parasite work and having a distinct influence
on the increase of the gipsy moth in the field, an elaborate series of
experiments has been conducted by Mr. R. W. Glaser and several
assistants for the purpose of securing information on the. identity
of the wilt disease (Pl. VIII) and the factors which are favorable to
its increase in the field.

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MAP SHOWING DISPERSION
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CALOSOMA SYCOPHANTA

IN

NEW ENGLAND
1914

This species has been found generally distributed in the territory between the red lin¢ =
and the Atlantic Ocean.

© Towns where a few specimens have been recovered

G scave Of Meg.
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Bul. 204, U. S. Dept. of Agriculture. ; PLATE VIII.

THE WILT DISEASE OF THE GIPSY MOTH. (ORIGINAL.)

Note the typical way in which these caterpillars hang when affected by this disease.

rd Se eae a Tt gl ae Rye oe ee Ci i

GIPSY MOTH WORK IN NEW ENGLAND. 13

This work has been carried on at the Bussey Institution, Forest
Hills, Mass., and a sublaboratory in charge of Mr. J. J. Culver has
been maintained during the summer at Worcester, Mass., where
special experiments have been conducted to determine the relation of
favorable and unfavorable food plants to the development of the
disease. A series of field experiments was also conducted in a selected
area at Lunenburg, Mass., by Mr. A. W. Young and Mr. R. T. Webber,
who made continuous observations in a limited area on the develop-
ment of the disease under field conditions, with particular reference
to the relation of temperature and humidity. Several other points
were selected in Massachusetts where continuous temperature and
humidity records were secured, as well as at the Lunenburg area,
and a careful compilation of this data is expected to give informa-
tion as to the weather conditions which are most favorable for the
development of this disease.

For a number of years the wilt disease has been found in the field
in nearly all places where heavy gipsy-moth infestation exists.
During the last year or two it has occurred in light infestations and
very few localities in the infested area are known where it is not
found to a greater or less extent.

The results of the season’s work indicate that the disease has been
slightly less prevalent during the past summer than the previous
year and this was particularly true during June and the first part of
July. Cool weather prevailed at this time. Late in July the large
caterpillars in many places were seriously affected, so that the in-
crease of the gipsy moth was not as great as was anticipated early
in the season. 7

The technical studies on the wilt disease are very difficult to con-

duct because it is almost impossible to secure healthy material for

experimental purposes. The organism is believed to be a filterable
virus and is so minute that it easily passes through the finest bacterio-
logical filters that have yet been devised. It belongs to the same
class of organism as yellow fever and a number of other contagious
diseases, although all of these were, at one time, supposed to be
caused by bacteria. The period when gipsy-moth caterpillars of
moderate size are available for experiments covers about six weeks,
and this adds to the difficulty of carrying on investigations on account
of the limited time when material can be secured. During the past
year it has been determined that the wilt disease, or a similar organ-
ism, affects eight of our common native caterpillars in addition to
the gipsy moth. It is also known to attack the silkworm (Sericaria
mort L.) and nun moth (Porthetria monacha L.), a fairly common
European species which is very destructive to pine. Good results
have been secured this year, but a large amount of work is necessary

14 BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE.

in order to establish the essential facts concerning the identity of
the organism and the conditions most favorable for its increase and
development.

FOOD-PLANT INVESTIGATIONS.

As has already been pointed out, the species of tree growth have
an important relation to the ability of the gipsy moth to increase
and cause serious damage in the field. Nearly 20 years ago food-
plant experiments were conducted in this country to determine the
species upon which the gipsy moth would subsist, and a long list of
food plants was published by Forbush and Fernald in their excellent
book on the gipsy moth. Most of these experiments, however, were
carried on by using large caterpillars and feeding them in jars or cages
in the laboratory. At that time it did not seem important to deter-
mine whether there was variation in the feeding habits of the cater-
pillars in different stages. As early as 1908 it was observed and
proven by an extensive field experiment that the first-stage cater-
pulars of the gipsy moth could not develop on white pine in the
absence of other food. This naturally led to the question of unfavor-
ability of other species to gipsy moth attack. In 1912 a careful
series of food-plant experiments was begun. Mr. F. H. Mosher took
charge of this work and has been furnished with a number of assist-
ants during the feeding season. The feeding was carried on in indi-
vidual trays, which were specially constructed for the purpose.
One hundred first-stage caterpillars were placed upon a branch of
foliage in each tray. In this way the feeding habits could be observed,
the foliage renewed daily, and it was possible to determine which
food plants were least subject to attack under laboratory conditions.
Similar experiments were carried on with caterpillars in the succeed-
ing stages. This work was continued in the summers of 1913 and
1914, so that up to the present time about 250 species of trees and
shrubs have been tested.

As a result of these experiments some of the more common species
are rated as follows:

I.—Species favored by the gipsy-moth larve in all stages:

Alder, speckled.! Oak, black.

Ash, mountain. Oak, chestnut.
Aspen.’ Oak, post.

Balm of Gilead.* | Oak, red.

Basswood. | Oak, scarlet.

Beech. Oak, swamp white. -
Birch, gray.! | Oak, white.

Birch, paper. | Poplar, big toothed.!
Birch, red.} Shadbush.'
Boxelder.! Willow.!

Larch. Witch hazel.!

a nr e——————————————
1 Species of low commercial value.

GIPSY MOTH WORK IN NEW ENGLAND. 15

II.—Species favored by the gipsy-moth larve after the first stage:

Chestnut. Spruce, black.!
Hemlock. Spruce, Norway.
Pine, hard.! Spruce, red.
Pine, red. Spruce, white."

Pine, white.

III.—Species not favored by the gipsy-moth larve but capable of
supporting it:

Beech, blue.' Maple, red.!
Birch, black. Maple, silver.!
Birch, yellow. Maple, sugar.
Cherry, black. _| Pignut.

Elm. . Sassafras. 1
Gum, black.! Shagbark.

Hornbeam, hop.!

IV.—Species unfavored by the gipsy-moth larve in all stages:

Arborvite. Fir, balsam.!
Ash, black.} Hackberry.
Ash, white. Locust, black.
Butternut. | Locust, honey.
Cedar, red.! Sycamore.!
Cedar, white. Tulip.

1 Species of low commercial value.

During 1914 many food plants were tested which do not ordinarily
occur in New England except when planted for ornamental purposes.
They grow to a greater or less extent in other sections of the United
States, and it was desired to make these tests in order to determine
whether these plants would be seriously damaged by the gipsy moth
in case it should spread from New England. The information is also
useful as a guide to the method of treatment which should be applied
in case a small colony should become established in some region
outside the present infested area. During the first two summers
that these experiments were carried on a sublaboratory was main-
tained at Worcester, Mass., where check experiments were con-
ducted. The food-plant work is now nearly completed and the
results will be brought together shortly for publication. In con-
nection with these experiments it should be said that a large number
of observations have been made in the field each summer relative to
the favorability of different species of trees and undergrowth to
gipsy-moth attack. This information serves as a check on the
laboratory experiments which are carried on under artificial condi-
tions. The observations in the field have in the main been made in
definite areas, which were selected for an entirely different purpose
and will be considered under the next experimental project.

16 BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE.

x

EXPERIMENTS IN DETERMINING THE INCREASE OF THE GIPSY MOTH IN THE FIELD.

In view of the importance of parasites, disease, and unfavored
food plants in reducing the imcrease of the gipsy moth, it seemed
desirable to secure definite data on the normal increase of this insect
in the field and the increase where these deterrent elements were
present in varying degrees. The most feasible way to determine ,the
increase is to compare the number of egg clusters in a given locality
from year to year. In order to do this arrangements were made in
the fall of 1911 to study field conditions in a systematic manner.
About 250 areas which have been designated as ‘‘observation points”
were selected throughout the infested area. This gave an oppor-
tunity for ascertaining the effect of latitude, seasonal variation, and
altitude on the increase of the species. In selecting these points an
attempt was made to secure as many pure stands of forest growth as
possible; also, to obtain areas of mixed growth where the proportion
of favored food plants varied. Areas were also secured where
different species of parasites had been liberated and where the wilt
disease had occurred abundantly or in a small amount during the
previous year. The degree of infestation was also considered in
making a selection and a number of points were obtained where the
trees had previously been defolhated to check against some where no
defoliation had resulted and the infestation was very light. After
an area was selected a tree was marked for a center and a circle 100
feet in diameter was laid out. Each tree within the circle was
numbered consecutively and a note made of its species, size, and
condition. In the fall, as soon as the foliage had dropped, a careful
count was made of the egg clusters on each tree. These results have
been secured and tabulated as well as exact information relative to
the number of egg clusters found on the ground and undergrowth.
Records have also been kept on the condition of the trees from year
to year, and the number of trees which died in each area has been
carefully noted. The condition of the territory surrounding these
points, as regards infestation, has also been noted. This work has
been supervised by Mr. C. W. Minott, but it has not been carried on
for a sufficient number of years to give all the exact information

desired.
The following table gives the gross number of egg clusters.found in
the points each year, and will be of interest as indicating in a general
way the severity of the infestation from 1910 to 1914. |

It will be noted that 170 points are given in the table. The balance
of the 250 which were originally selected have been discontinued,
owing to destruction by fire, promiscuous cutting by the owners, or
for other reasons. The area in the points aggregates 30.18 acres,
and the surrounding territory which has been watched brings the
total under observation up to 863.1 acres. For convenience, the

GIPSY MOTH WORK IN NEW ENGLAND. 1%

infested territory has been divided into five sections, and the towns
in which the points were located are indicated on the accompanying
map.

Taste III.—Gipsy moth egg clusters recorded in observation points, 1910-1914.

Egg clusters.

: Number
Locations. of points.
1910 1911 1912 1913 1914

Eastern New Hampshire and Maine....... 32 2, 074 31, 751 29, 637 26,147 18, 234
Western New Hampshire................- 33 14, 885 23, 032 28, 618 9, 603 13, 228
Northern Massaehusetts..................- 34 29, 399 47,419 30, 345 17, 603 31, 316
Western Massachusetts...................- 30 10, 742 26, 409 28, 301 9, 763 17, 159
Southern Massachusetts..................- 41 11, 486 39, 319 42, 451 8, 222 31, 065
ARCH O POMC OS aac cw laisc cece clec cece 170 68, 586 167, 930 159, 352 71, 338 111, 002

The count of the egg clusters recorded under 1910 was made in the
fall of 1911 and covered all clusters which were found to have hatched
and therefore belong to the 1910 brood of moths. This count was
more or less inaccurate, as many of the egg clusters were removed
from the trees after a year’s exposure to the elements. The count
indicates, however, that there was a large increase in infestation
between 1910 and 1911, and that in 1912 the gross infestation was
slightly reduced. A heavy reduction occurred in 1913, while in 1914
a considerable increase was noted but not nearly as great as was the
case from 1910 to 1911.

The conclusion which will inevitably be drawn from these figures

will not apply to other localities in the infested area. There are many

locations where a marked increase was noted in 1913 or where a
marked decrease was noted in 1914, but taking the territory as a
whole it gives a general idea of the trend of increase or decrease for
the period covered.

Knowing the conditions, one can not fail to be impressed with the
results that have already become apparent from the introduction of
parasites and the work of the wilt disease. Although the season of
1914 was not as favorable to the natural enemies as was the case in
1910, the proportional increase in the number of egg clusters was
considerably smaller. Unfavored food plants have, of course, been
instrumental in holding down the increase in some of the points, but
the amount of infestation in points where unfavored food predom-
inates has remained rather constant, so that it has not been as great
a factor in the reduction noted as the other elements just mentioned.

Much careful work has been required to secure this data. For
about six months in each year upward of 20 men have been engaged
in this work. During the summer a part of the men made observa-
tions on the feeding habits of the gipsy moth caterpillars on different
food plants in their sections. Observations on the presence of

18 BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE.

natural enemies were also made and from time to time collections of -
ege clusters or caterpillars near the points were obtained and sent
to the laboratory in order that the percentage of parasitism might be
determined. This work should be continued in order to determine
whether after the natural enemies become firmly established the
outbreaks of this insect will be periodical over a large territory or
whether, as is the case at the present time, the smaller colonies will
increase so that stripped areas will be found scattered over the entire
region.
DISPERSION WORK.

For the past three or four years considerable attention has been
paid to the means by which the gipsy moth spreads. As the female
moth does not fly it is apparent that the dispersion of the species
must be very slow unless it is carried by other means. Egg clusters
may be transported on lumber, forest products, Christmas trees,
or other material which is likely to be shipped long distances from the
infested area. This matter has been given careful consideration and ©
means have been taken to prevent the spread of the moth in this way.
Information concerning methods used are given under the quarantine
part of this report.

In the spring of 1910 a number of experiments were conducted which
showed that first-stage gipsy-moth caterpillars may be carried by the
wind, and the information secured at that time has been published.

Since this work was carried on more elaborate experiments have
been conducted by Mr. C. W. Collins and assistants, to obtain long-
distance records on the spread in this manner. A study has also been
made of the likelihood of the insect being spread by caterpillars drifting
in streams, or by wood or other material which is infested with egg
clusters floating in rivers and becoming lodged in territory which was
not infested. At present wind spread seems to be the chief natural
means by which the insect becomes established in new territory.
The trend of the spread is toward the north and northeast on account
of the fact that the warm prevailing winds before the first of June,
when the caterpillars are in the first stage, usually blow in those
directions. This has resulted in a large increase in the area infested
in Maine, and the territory in that State will probably continue to
extend as long as large areas are seriously infested in New Hampshire ~
and Massachusetts. The western spread of the insect has probably
been greatly retarded by reason of the fact that low temperature,
causing the caterpillars to be inactive, has prevailed when the
winds came from the east or northeast. Heretofore serious infesta-
tion did not occur in southeastern Massachusetts or Rhode Island;
hence winds from the southeast were not an important factor in

1 Burgess, A. F. The dispersion of the gipsy moth. U.S. Dept. Agr., Bur. Ent., Bul. 119, 62 p., 16
pl., 6 fig., 1 map, Feb. 11, 1913.

GIPSY MOTH WORK IN NEW ENGLAND. 19

causing spread into Connecticut or the area in Massachusetts south
of Worcester. Recently, however, the infestation has increased to
a great extent in southeastern Massachusetts and Rhode Island,
and unless vigorous means are taken to abolish these sources of sup-
ply, rapid infestation of eastern Connecticut and territory in Massa~-
chusetts lying immediately north of that State will result. In fact,
during the past season a large increase has been found in the western
tier of towns in Rhode Island and the eastern tier in Connecticut.
In eastern Connecticut the white oak, which is one of the most favored
food plants of the gipsy moth, is exceedingly common in the wood-
lands, and the difficulty of controlling the moth under these condi-
tions is very ercat.

A series of experiments has been conducted to determine how pe
male moths will be attracted by the females. The purpose is to deter-
mine the probability of scattered females being fertilized if they occur
at a long distance from a gipsy-moth colony.

SECONDARY INSECT INVESTIGATIONS.

In the fall of 1912 large numbers of oak trees in the areas that had
been defoliated by the gipsy moth were found in a dying condition.
Examination showed that many of the trees had been attacked by a
bark borer, which proved to be Agrilus bilineatus Web. The matter
was taken up with Dr. A. D. Hopkins, in charge of Forest Insect
Investigations of the Bureau of Entomology, and arrangements were
made for cooperative study of this insect. Dr. Hopkins was to direct
the work, and the salary and expenses of an assistant, Mr. H. A. Pres-
ton, who was to give his entire time to the work, were to be paid by
this branch. Investigations have been carried on and the life history
of the insect worked out. It appears from the information secured
that continuous work on this project is not necessary, and the coopera-
tive arrangement was discontinued July 1, 1914. The data relative
to the life history and habits, as well as control measures, is in the
hands of Dr. Hopkins and will doubtless be published at an early date.

For the information of woodland owners who wish to preserve their
oak trees it can be stated that all trees which are in a dying condition in
September should be marked so that they can be cut during the winter.
The wood should be removed from the lot and if it can be used for
fuel the hibernating larve will be destroyed. Inasmuch as the oak
is very favored as afood plant by the caterpillars of the gipsy moth and
as the Agrilus beetles prefer to attack weakened trees, it would seem
rather difficult to preserve oak growth unless considerable expense was
involved in spraying or treating gipsy-moth egg clusters in order to
keep the trees in a vigorous condition! This is impracticable in most
woodlands in the infested area. Park or ornamental trees can be
handled in this way and the cost is not prohibitive.

20 BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE.
RESULTS OF EXPERIMENTAL WORK.

Many of the experimental projects which have been undertaken are
nearing completion and detailed reports will be published later.

The information on food plants will now form a definite basis for
practical work, and as has been brought out by the observations in
Europe on both parasites and food-plant conditions, it will be neces-
sary to bring about in our forests a great reduction of the favored food
plants of the gipsy moth before natural enemies can be expected to
keep this insect within reasonable bounds.

The parasites and wilt disease, as has already been shown, are doing
effective work, but the results would be greatly amplified by eliminat-
ing favored food plants.

The study of the increase of the moth in the field furnishes valuable
data on all phases of the forest control problem, while the work on
dispersion is of special value in connection with the field control work
which is being carried on.

Secondary insects are important inasmuch as they may prevent the
recovery of many trees which have been defoliated and which would,
under normal conditions, gradually recover.

SILVICULTURAL WORK.

During the time the gipsy moth has been known to exist in this
country it has done an immense amount of damage to tree growth of
the infested region. The injury has caused the death of many of the
trees attacked or the retardation of their growth and development,
and has produced conditions favorable to the increase of secondary
enemies. The tree growth affected may be divided into three classes,
(1) fruit trees, (2) shade or ornamental trees, and (3) forest. trees.
All have suffered severely, but owing to their greater value and
relatively smaller numbers’it has been possible to prevent a large
amount of the injury by applying hand methods of suppression to
fruit and shade trees. Gipsy-moth damage to forest trees, however,
can not be controlled in the same way owing to the great expense
involved, hence the problem of preventing damage in woodlands is a
serious one. In some European countries this has been solved to a
considerable extent by growing species which are not so susceptible
to gipsy-moth attack. The investigations on the food plants and
feeding habits of the gipsy moth indicate that the work of eliminating
the most susceptible and encouraging the growth of those that are
not favored as food by this insect is likely to give good results. As
this work involves, to a considerable extent, the practice of silvicul-
ture, the Bureau of Entomology requested and received the coopera-
tive assistance of the Forest Service, and these two branches of the
Department of Agriculture are now working together on this problem.
Mr. George E. Clement, who was formerly an assistant in the Forest

1 Negev AEE IER

GIPSY MOTH WORK IN NEW ENGLAND. 21

Service, has been appointed to take charge of the investigations along
this line. The table given under the ‘‘food-plant experiments”’ indi-
cates in a general way the degree of susceptibility to moth attack of
some of our more common forest trees. Certain species, however,
are of little commercial value, and it is desired to discourage their
growth, as well as those that are particularly susceptible to gipsy-
moth attack. In the case of valuable species that are susceptible to
attack and for the growth of which a large portion of the infested region
is favorable, the only step which can be taken is to determine whether
or not they can be sufficiently protected from serious damage by
associating with the less susceptible species in small proportions. Of
course, the presence of these species may jeopardize the safety of the
associated species which would otherwise be immune. However,
before abandoning these species careful experiments will be made to
determine whether there are associations with which they can join with
safety.

The chief fact that reduces the liability of certain species of trees,
particularly conifers, to gipsy-moth attack is that the very young cater-
pillars do not feed upon them. Therefore, if there are present no trees
or undergrowth upon which the young caterpillars will feed and thereby
develop to a size which enables them to attack conifers or similarly
susceptible species, they will not be attacked. Thus it appears that
certain species can be grown pure or in exclusive association and be
free from gipsy-moth attack. Any system of forest management
should endeavor to produce in a given area only trees of commercial |
value, and the foregoing lists (pp. 14-15) mdicate the most suitable
species for selection.

In converting a given stand of timber into one which shall be im-
mune from gipsy-moth attack, the different classes of trees should be
considered for removal in the following order:

(1) Trees of naturally low commercial value and susceptible to
gipsy-moth attack.

(2) Trees of low commercial value on account of growing in un-
favorable situations and susceptible to gipsy-moth attack.

(3) Trees of commercial value, favorably situated, and subject to
gipsy-moth attack.

(4) Trees of naturally low commercial value, but not liable to
gipsy-moth attack if properly associated.

(5) Trees of low commercial value on account of growing in un-
favorable situations and not liable to gipsy-moth attack.

(6) Trees of commercial value favorably situated and not lable
to gipsy-moth attack.

Silvicultural conditions in the woods of the infested region are very
poor. Through repeated fires and heavy and inconsiderate cutting,
the growth of weed trees has been greatly favored and the growth of

|
|

ef

ics

22, ‘BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE.

some species has been favored in situations quite unsuited to their

requirements. This is particularly true in the case of the oaks and ©

gray birch. These species constitute a very large proportion of the
deciduous growth of the region and are very susceptible to gipsy-
moth attack. On a great deal of the area now covered by these
species the white pine would grow to much better advantage, would
yield a much more valuable product, and if pure, or nearly so, would
prove immune to gipsy-moth attack. The white pine reproduces
itself readily under favorable conditions, and is already fairly
abundant in numerous localities. For these reasons the white pine
recommends itself very strongly as a substitute for the existing moth-
susceptible species, and this species has been considered to a very
large extent by this department in its experiments to create a safe
stand of timber. The deciduous species which are of value and im-
mune to gipsy-moth attack require most favorable situations for
their profitable development, and such situations are very few and of
small area. An exception in the case of chestnut may be made in

this connection. This is a valuable tree and one well suited to grow

over a considerable area. Its growth is not recommended on account
of its susceptibility to the widespread and fatal chestnut blight. But,

like the red oak, it may be found possible to grow it satisfactorily in |

small numbers with other species.
EXPERIMENTAL WORK.

The experimental work has been conducted by means of small
areas known as ‘‘sample plats.’”’ These vary in size from one-half
an acre to 6 acres and occur both scattered and grouped in different
parts of the infested region. ‘They are necessarily located on the
lands of private owners who are willing to submit their lands to this
use.

An effort has been made to distribute this work as widely as pos-
sible over the infested region. (Pl. IX.) In this way the greatest
variety of conditions is encountered and the results are available to
the greatest number of woodland owners. Each sample plat varies
from another in one or more of the following points: Composition of
stand, age of stand, degree of infestation, and method of treatment.
Each sample plot generally consists of two parts. One of these is
the portion upon which actual experimental work is done and the
other serves as a control or check plat. Upon the latter nothing
whatever is done, as its purpose is to provide a means of comparing

results under natural and artificial conditions. The corners and —

boundaries of all plats have been plainly marked, and the areas
surveyed and mapped. All trees 1 inch and over in diameter have
been calipered on each plat and control, and the measurements
recorded. Forest descriptions of each plat have been written.

|

GIPSY MOTH WORK IN NEW ENGLAND. 93

Where small white pines have occurred in any quantity they have
been counted and the numbers have been recorded by foot-height
classes. The best available indication of the degree of gipsy-moth
infestation seems to be the number of egg clusters, and for this
reason the egg clusters have been counted on each plat. Egg
clusters will be counted periodically in the future in order to determine
the effect of treatment upon the infestations.

After the foregoing steps have been taken, the growth on each of the
managed areas has been thinned. Different silvicultural systems have
been used, but in general the object has been to remove the greatest
number of susceptible trees consistent with the silvicultural require-
ments of the trees to be left. In some cases the bulk of the stands
consisted of susceptible species, and in these the thinning made was
preliminary to a later clear cutting.

After cutting, the number of trees of different diameters and species
have been counted and recorded, the amounts of products have been
measured and recorded, brush has been piled and burned, careful
notes of the changed conditions have been made, and an effort has
been made to compute the cost of the work and the value of the prod-
ucts on each plat. In some cases numbers of small naturally pro-
duced white pine have been supplemented with planted 2-year-old
seedlings from the nursery. In cases where plantings were made the
cost of the seedlings and the planting was borne by the owner of the
woodland. Im addition to the sample plats already mentioned, one
10-acre tract has been selected in each of the following towns in New
Hampshire: Peterboro, Franklin, Warner, and New Durham. The
erowth on all these plats is largely inferior hardwoods which are par-
ticularly liable to gipsy-moth attack. The infestation in each case
isnot heavy. As there is more or less white pine growing among the
hardwoods the plan is to cut the latter clean and to replace these
trees by planting enough white pine to produce a stand which will be
free from gipsy-moth damage. The results of these experiments will
not be available for several years, and during this period careful notes
on conditions will be made.

MIDDLESEX COUNTY FOREST SURVEY.

In order to get some definite information concerning the distribu-
tion of the various kinds of timber stands in the region, a rough forest
map of the county of Middlesex in Massachusetts has been made.
This work has shown that the forest growth is very uneven and com-
plex, and that there is a wide variation in the composition of stands
within relatively small areas. The existing growth of trees on any
area indicates very infrequently the growth for which the conditions
on the area are best suited. From data secured by this survey and
observations made througthout the infested region, the crying silvi-

24 BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE. + —

cultural need of the woods is obviously a great reduction of their
diversity and the replacement of a large portion of the species by
those which have a greater commercial value, and for which the con-

ditions for growth are much better adapted. The steps needed to

accomplish this are in many instances precisely those which appear
to be necessary in controlling gipsy-moth attack by silvicultural
practice.

»

PROPOSED FOREST EXPERIMENT.

In order to determine the practicability of carrying on an experi-
ment over a large area preliminary surveys have been made of the
forest growth in the town of Winchendon, Mass. This work has been
attempted in cooperation with the State forester of Massachusetts,
Mr. F. W. Rane. The original growth in this town was undoubtedly
coniferous, but there has been considerable cutting and as a result
hardwood growth of various species has become established. Oak
does not predominate, however, in this region and it is hoped that
sufficient cooperation can be secured from the woodland owners in
the town to handle the forest area so as to bring it into a growth
which will not be susceptible to gipsy-moth attack. The preliminary
survey has been completed and the data are now being compiled with
a view to determining whether a plan of this sort can be worked out
on an extensive area.

SCOUTING WORK.

The scouting work consists in examining the territory along the
outside border of infestation, and in treating the gipsy-moth colonies
adjacent to the border for the purpose of preventing spread of the
insects to other parts of the United States. This work 1s in charge
of Mr. L. H. Worthley, who is assisted by Mr. H. L. McIntyre. The
territory is divided into six sections with the following men in charge
of asection: Mr. D. G. Murphy, Worcester, Mass., H. A. Ames, Athol,
Mass., H. N. Bean, Keene, N. H., F. W. Graves, jr., Bradford, N. H.,
F. W. Foster, Plymouth, N. H., and C. E. Totman, Canaan, N. H.
Parties consisting of five trained scouts in charge of a foreman are
detailed to make the examinations and treat the infestations, each
general foreman having from 5 to 10 crews of scouts under his super-
vision. In order to check up the thoroughness with which the work
is done in the lightly infested territory, a party, usually consisting of
two experienced men who are known as special scouts, examines the
work after the regular imspection has been made in order to see

whether egg clusters of the moth have been missed and that the .

work was thoroughly done by the scouts. Each scout is required to
place a characteristic mark on every tree examined by him so that
the responsibility for leaving egg clusters can be readily determined.
By following up this plan the force is maintained at a high degree of

PLATE IX

ace
= es

MAP SHOWING TOWNS IN NEW ENGLAND

IN WHICH

SILVICULTURAL EXPERIMENTS ARE BEING CONDUCTED
1914

©@ Towns indicated thus

SCALE OF MILES
os 6 9 1 bo + 2
——

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LTT Te ea Re ES eal ede
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MAP SHOWING AREAS IN NEW ENGLAND
THE GIPSY MOTH AND THE BROWN-TAIL MOTH

Hoke:

re

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Bitte li
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Ss, ;
3 GIPSY MOTH WORK IN NEW ENGLAND. 95

efficiency, the careless and negligent men being dropped from the
rolls. When large colonies are found crews of woodchoppers are
employed temporarily to cut out the worthless trees and clean up the
undergrowth in order to render the area in condition for effective
operations.

The accompanying map (Pl. X) shows the territory which was
known to be infested by the gipsy moth in the fall of 1913. In organ-
izing the work a large party of scouts was sent to Maine for the pur-
pose of determining whether the infestation had spread beyond this
line. The results of the examination show that a large number of
- towns are infested outside the border previously established. The
work was continued until late in December, when it was necessary to
transfer the men on account of deep snow and extremely cold weather,
the temperature for a number of days being as low as 20° to 25°
below zero. In all, 155 towns were scouted in Maine, and of these 81
were found infested. The increase in the number of towns over that
_ of previous years is largely explained by the fact that during the
- winter of 1912-13 the scouting work was not completed on account

of snow and also because of the undoubted dissemination of the moth

_ by means of the spread of the small caterpillars by the wind. The
manner of this kind of spread has already been explained in this
report. Suffice it to say, the general trend of dispersion of this insect,
has been toward the north and northeast on account of the fact that
the prevailing warm winds during the time the caterpillars are
hatching blow from the south and southwesterly directions. The work
was continued from January until April in New Hampshire, Massa-
_ chusetts, Rhode Island, and Connecticut.

On February 3, 1914, a report was received that several gipsy-moth
_ egg clusters had been found on an estate at Bratenahl, Ohio, a suburb
_ of Cleveland. The matter was at once investigated and two experi-
_ enced scouts were detailed to make an examination of the estate and
_ the surroundings. At the time the work was done there was con-
siderable snow on the ground, making inspection work difficult.
Seven new egg clusters were found and treated and later in the season
_ the colony was burlapped and the trees sprayed. The work in Ohio
_ was done in close cooperation with the Ohio Agricultural Commis-
sion, and work in the colony since the original scouting was done has
_ been carried on by the assistants of Mr. N. E. Shaw, State nursery and
orchard inspector.

On May 7, 1914, a report was received from Mr. George G. Atwood,
chief of the division of horticulture of the State of New York, that a
sipsy-moth colony had been found at North Castle, Westchester
County, N. Y. Inspectors from this office were detailed to treat egg
clusters, and several experienced scouts were transferred to assist in
stamping out this colony. The principal infestation occurred on a
large estate, and the caterpillars began hatching soon after the first

26 BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE.

egg clusters were found. A considerable area was scouted around the.
infestation, and egg clusters or caterpillars were found over an area of
about three-fourths of asquare mile. Many of the trees were growing
on rough and rocky soil, so that 1t was very difficult to do thorough
work. About 15,000 egg clusters were treated during the month of May.

In addition to the scouting work already mentioned, a special
examination was made of the entire town of Geneva, N. Y., but no
gipsy-moth egg clusters were found. In 1912 a small colony was
found in this city. It has been very thoroughly treated by the
assistants of the commissioner of agriculture, and it is now believed
that the insect has been exterminated. The scouting party detailed
for the Geneva work spent one week in examining trees in Seneca
Park, Rochester, N. Y., but no traces of the moth could be found.

Special scouting work was carried on in the towns of Lenox, Stock-
bridge, and Great Barrington, Mass., during the winter. Infestations
have previously been found in these towns, but the examination
resulted in finding but one egg cluster in Great Barrington, one in
Stockbridge, and two in Lenox, indicating that good results have been °
secured from the treatment which had been applied during the pre-
vious season. A careful inspection was also made in the town of
Wallingford, Conn., which was found infested some years ago, but no
ego clusters were discovered.

The following table shows the number of towns which have been
scouted for the gipsy moth and the number of new towns which
were found infested during the winter of 1913-14.

Tasie LV.—Scouting operations for the gipsy moth during the winter of 1913-14.

: Towns Newly

State. scouted. infested.

Mamet. 2! oa. oksece 155 81
New Hampshire...-. 73 6
Massachusetts......-- 36 iG
Riuhodetsland 2-222. 19 17
Connecticut........-- 13 10
IN@we On -- 2. snee 3 1
QIOE Ae es ree 1 1

In nine towns in New Hampshire and two in Massachusetts, infested
in 1912-13, no infestations could be found the following winter, and
recommendations were made that these towns be excluded from the
quarantined area. This was approved by the Federal Horticultural .
Board, and the border towns of the area quarantined for the gipsy
moth include only those that have been found infested during the
past winter.

The plan of the work has been to examine the territory in Maine
chiefly for the purpose of securing data as to where the quarantine
line should extend. It is impossible to prevent the spread of the
small caterpillars by the wind, and it has therefore been deemed
advisable to confine the clearing-up work along the border to the ter-
ritory in New Hampshire, Massachusetts, Rhode Island, and Connec-

GIPSY MOTH WORK IN NEW ENGLAND. 21

ticut. Accordingly early in the spring arrangements were made to
place tanglefoot bands on trees in all the dolonies about three towns
wide along the border and from the time this work began the greater
part of the scouting force was transferred to the work of apply ing
and patrolling these bands.

In the colony in Westchester County, N. Y., 6,000 tanglefoot and
4,000 burlap bands were applied by the inspectors of the State depart-
ment of agriculture. The State purchased a high-power spraying
machine and very thoroughly sprayed the infested area and surround-
ings. The colony in Ohio was similarly treated by the State officials,
and in both cases excellent results have been secured. This office has
kept in constant touch with the work in these States and has also had
a representative directing the work in the Berkshire Hills infestations
in Great Barrington, Stockbridge, and Lenox.

Inasmuch as many of the new infestations were found on apple
trees during the winter, a record has been kept of all such trees
inspected and of the number of miles of roads scouted by the men.
This information is given in the following table:

Taste V.—Results of scouting operations for the gipsy moth.

: Miles of | Tanglefoot
Towns Colonies Egg clus- | Apple trees
State. : road trav- | bands ap-
scouted. found. ters found. | inspected. Aled plied.
Tica, SO gers Sar oe aaa eerrielo bal ashes (seats eee o 764, 081 ASTER hye. av RRaNe:
New Hampshire Lite 3a ae eB 73 1,656 25,427 | 1,354,908 4,334 68, 336
MEISSACHUISO LUSH canes ee ee 36 794 11, 987 484, 731 DDoS 58,315
FunoUder sands 2 22 oe ee 19 1 309 1 207 232, 190 987 5,324
Monnecticut. <2... 4 ee Se * 118} 1157 1124 332, 036 884 4, 767
Aor Lc ase ature Gav ems 296 2,916 37,745 | 3,167,946 13,526 136, 742

1 In a number of these colonies pupa cases only were found.

The following conditions found in 1913 and in 1914 are of interest.
In New Hampshire no egg clusters were found in 198 of the colonies
that had been treated during the previous years, and in 641 of the
1,656 colonies found in the winter of 1913 no larve were found in the
spring of 1914. In Massachusetts no egg clusters were found in 68
of the colonies that were treated during the winter of 1912-13, and in
124 of the 794 colonies located in the fall of 1913 no larvee were found
in the spring of 1914. In Rhode Island 276 of the 309 colonies found
and treated in the fall of 1913 failed to produce larve in the spring of
1914. In Connecticut 136 of the 157 colonies treated in 1913 failed
to produce larve the following spring.

During the summer of 1914 woodland scouting was carried on in
Thompson, Conn., and Rutland, Mass. The former town is heavily
wooded and is reported to contain about 30,000 acres of forest, a con-
siderable part of which is oak growth. As a result of the examina-
tion of the woodland in this town 73 gipsy-moth colonies were discov-
ered. All of them were small infestations, indicating that the species
is established and is well scattered through the woodland.

-oee

=, pee

§

28 BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE.

GENERAL RESULTS SHOWN BY SCOUTING WORK.

The scouting work for the season has shown very encouraging
results. In addition to the large number of towns along the outside
border where the infestation has been greatly reduced or where it-has
been cleaned out during the past year, an excellent showing has been
made in a number of badly infested towns in Massachusetts and New
Hampshire which are just inside the border. In a large number of
these towns which were found severely infested in the winter of
1912-13, a large decrease in the number of egg clusters has been found
this year. In the town of Bradford, N. H., where over 3,000 egg
clusters were treated during the former year, only 200 were found this
season. In Hillsboro the records show a reduction of from 8,000 to
500, although the number of small colonies, many containing a single
egg cluster, has increased. In Henniker and Warner, N. H., a large -
decrease has also been noted and the same is generally true in the
border towns where work is being carried on.

The work on the tanglefoot bands during the entire season gave
very gratifying results, and a very large number of the colonies where
caterpillars were present early in the season showed no caterpillars
or pupe at the close of the work on tanglefoot bands on August 1.
Only a few caterpillars were found in the western part of the area in
New Hampshire, Rhode Island, and Connecticut.

No caterpillars were found in Lenox, Stockbridge, or Great Bar-
rington, Mass. About 400 yards from the old infested area in the
latter town 43 egg clusters were found in a rock heap during the cater-
pillar season which, of course, was under the snow when scouting -
work was done. Some very thorough work was done at this infesta-
tion, and only one pupa was found this season. Of course there is
danger of some spread from it, and during the coming season some
very thorough scouting will be done in this vicinity.

No caterpillars were found at Wallingiord, Conn., this season. .

In the badly infested woodland colony in Orange, Mass., where
some 1,000 egg clusters were located, there were but 1,182 larve
found during the summer.

The spraying work during the summer gave very satisfactory
results, treatment being applied in border towns from Hubbardston,
Mass., as far north as Andover, N. H. Many of the localities where
spraying was applied were difficult to reach on account of being
inaccessible from roads or water supply, but owing to the careful plans
made by the foremen the work was not greatly handicapped on this
account. In a number of cases the owners of the areas which were
infested offered every cooperation possible in facilitating treatment. .
A few cases have been found, however, where spraying could not be
attempted on account of the unwillingness of the owners to have their
pasture trees treated because the grass was needed for grazing stock.
In instances of this sort the infestations were cared for by creosoting
egg clusters and destroying the caterpillars under tanglefoot bands. \

— Re SETS PRES
: ve

ENGRAVED AND PHINTEN? B+ THE U-S.GROIDGIGAL SUPVLy

“

" fart Nid pg 0a Kk

%

i PLaTe XI
a) ‘ie te ES X = S e

MAP SHOWING
GIPSY MOTH OUARANTINE DISTRICTS
1914

_——

GIPSY MOTH WORK IN NEW ENGLAND. 29
BROWN-TAIL MOTH SCOUTING.

The spread of the brown-tail moth is not easily controlled by arti-
ficial means unless the insect can be reduced to minimum numbers.
Owing to the large territory over which the insect has spread, it is
not possible to carry on extensive scouting or control work by the
use of hand-suppressive measures. During the year a considerable
area, however, has been examined in Maine, New Hampshire, Ver-
mont, Massachusetts, Connecticut, and New York, and areas have
been found infested where the insect was not known previously to
exist. The work of the commissioner of agriculture of Vermont and
his assistants has been very effective in reducing the infestation in
that State. The principal new infestations were found in Connec-
ticut, and a greater part of these were located by the assistants of
the State entomologist. Several webs have also been found on
Fishers Island and Long Island, N. Y., so that, in all, four towns on
these islands are known to be infested. The New York infestations
were discovered by the inspectors employed by the State department
of agriculture, and several scouts from this office were sent late in
the spring to check up the work and cover a part of the area

concerned.
QUARANTINE WORK.

The quarantine work is supervised by Mr. D. M. Rogers, who is
assisted by Mr. Harry W. Vinton, and the operations are confined
to the territory in New England and New York which is infested
by the gipsy moth and the brown-tail moth. As a result of the
provision of the Federal plant quarantine act, which was passed
by Congress August 20, 1912, a domestic quarantine’ has been
declared by the Federal Horticultural Board, covering the territory
infested by each of these insects. While the legal authority for
declaring quarantine is vested in the board, the cost of adminis-
tering the work is defrayed by the appropriation for the Bureau
of Entomology for ‘‘ Preventing the spread of moths.’’ The object
of this work is to prevent egg clusters or larve of the gipsy moth,
or winter webs of the brown-tail moth, from being carried out of
the infested areas on shipments of trees or forest products. The
regulations for enforcing this quarantine provide that all material of
this character before being accepted for shipment to points outside
the infested district must be inspected and must be accompanied
with an official certificate of the Federal Horticultural Board stating
that an examination has been made and that the material is free
from infestation. Shipment of Christmas trees and similar material
to points outside the quarantined area is prohibited. In order to
facilitate the work, the infested territory has been divided into 22
sections and a competent inspector has been placed in charge of

1 For details, see Notice of Quarantine No. 17, of the Federal Horticultural Board, effective Aug. 1, 1914.

30 BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE.

each. (Pl. XI.) Itis the duty of each inspector carefully to examine .
all lumber or forest products, cordwood, telephone poles, railroad
ties, tan bark, etc., which may be shipped from any points in his
district to points outside the infested area after the proper application
_ has been made and to issue certificates of inspection if no infestation
is found. Im accordance with the provisions of the quarantine
regulations, transportation companies are required to reject ship-
ments which are not accompanied with proper certificates. During
the season when nursery stock is being moved, examinations are
made of all woody plants which are consigned to points outside the
quarantined area. A number of special inspectors are employed for
this purpose in addition to the men engaged on the regular lumber-
inspection work. In order that this work may be of the most thor-
ough character so as to safeguard purchasers in other parts of the
United States, a tree-by-tree inspection is made of all trees and
plants growing in the nurseries before they are dug for shipment.
Another inspection of the plants is made at the time they are being
packed for shipment. During the fiscal year 1914, 17,076 shipments
have been examined and 4,476 specimens of the gipsy moth and
1,435 specimens of the brown-tail moth in their various stages have
been found and the insects destroyed. This has resulted in preventing
these pests from spreading to many localities not now infested. The
destinations of these shipments ranged as far south as Jacksonville,
Fla., as far west as Prineville, Oreg., and as far north as Montreal,
Quebec.

The destination of shipments on which infestations were found
and destroyed are given below:

Number of | Number of Number of
State. shipments. | State. shipments. State. shipments.
OUTED Gs ee ees Se A PDR RIRIG Seaton ane tect ee 12)| Pennsylvania-23!--- 3. ee 10
Monnechicttcsseaa-—~ 4. -55~ 25 dM Chisan sen smear ee 4 | South’ Carolinas 22-5 s-- 1
District of Columbia.-..-....-- A | PMissourizees 2 conse ee se ena 5 |S Vermontss.: 222-5 see ee ees 35
WIOTIO ae ees a: Sac se a once o |, New Hampshires- 227 :2)-5--- 7 | NMirginide ce ee: sees He
GEOLMIAe eo aeteee ooinseas-- 1 ATEN CWal CISC Vinca ee eee Th.) Canadas 2 52) ace ae eee 6
MNOS see ee snes oe = 14) New tN Orkecce 25> sees ee o4,| England. c-. .cees. se oeee eee 1
NO WAS eee ae aw cree ee ete, | EN Orth @arolinase esse eee 1 ere
Maryland: sos20 oe eee see ee Zu Ohi Owes. eee eee coer ee iby)
Massachusetts. - ...-.2-2..--- 24 WOTEC ONE 2.0) 52:54 Pane ae ee 1

BROWN-TAIL MOTH QUARANTINE.

The enforcement of the brown-tail moth quarantine is conducted in
connection with the inspections carried on to determine whether ship-
ments are infested with the gipsy moth. It is not necessary, however,
to inspect lumber for this purpose. Deciduous nursery stock is
examined and all webs of the moth destroyed before shipments are
permitted. In order to prevent as far as possible the carriage of the
adult female moths on trains, inspectors have been placed at several
main railroad junctions along the border of infestations to examine
the trains during the time the moths are flymg. These insects are
strongly attracted to bright light and the results which have been |

GIPSY MOTH WORK IN NEW ENGLAND. 3]

secured from these inspections have been very satisfactory. The
inspection work in 1914 began on July 6 and was continued until
July 31.

The stations where trains were examined and the number of adults
found are given below: |

Brown-tail Brown-tail
Station. moths found. Station. moths found,
TRG UWS, RUSE Ea ee UGH PANO thi stractordaiNe Elaaeeie smeeetiees sae eee 0
MUBEEETTOIOMI LASS hres actis oe ccc case tee cece OM oprineticld Masse eee ee eee eee ere see J
SUELERE Ta GINS 18 Ue ta ie Poe ee a GUUSt.voOhnsSburyyVitssesscce pa ets eo oreo Sie eee a 457
PMMOLONOON Me seerer eek se Seca Sees ORF NVVICLISHEUEN OD, Water Sasa ae Seale iste ene eea Tae). ee 247
New London,Conn....... Ee A ep eee TAS NVDIUteVRIVer UNC GON Vite eee cence eee 1,484

In addition to the foregoing, 296 adults were found and destroyed
at are lights in White River Junction, Vt.

RESULTS OF QUARANTINE WORK.

The results of the quarantine work have been very satisfactory,
Only one infested shipment of plant products has been known to
pass out of the territory and it was promptly returned.

Several carloads of stone and quarry products have recently been
found infested with gipsy-moth egg masses and a quarantine was
declared by the Secretary of Agriculture on October 23, 1914. Such
products must now be inspected and certified the same as plant
products.

Considering the number of infested shipments that have been
found and the wide range of country to which they would have been
sent if the egg clusters had not been found and treated, it is safe to
assert that this work has resulted in enormous saving of money
value to the agricultural and forest interests of the United States.

COOPERATIVE WORK.

Since the Federal work was commenced, active cooperation has
been secured from the States in which operations were being carried on,
While the organization of the State force and that of the Government
force are entirely distinct the work is planned in such a way as to avoid
duplication and to secure the best results. The general plan is for
the Bureau of Entomology to concentrate its efforts in stamping out
colonies in the territory along the western border of infestation from
Lake Winnipesaukee to Long Island Sound, and to carry on as much
work as may be necessary in eliminating the isolated colonies that
have been found in New York, Ohio, western Massachusetts, and
Connecticut. The State officials concentrate their efforts m the ter-
ritory inside the border towns. Owing to the hearty spirit of coop-
eration that has existed between the Bureau of Entomology and the
officials in New York, Ohio, and Connecticut, where isolated colonies
are present, it has not been necessary for this office to expend much
money for control work, as the States concerned have made every
effort to stamp out these colonies. A system of following up and

32 BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE.

checking over the work done by these States has been adopted, so
that very satisfactory work has resulted. In the distribution of
natural enemies arrangements have been made to cooperate with the
State officials, and this has resulted in the establishment of more
colonies of parasites than would otherwise have been possible. An
arrangement has been made with the Massachusetts State Board of
Agriculture so that speakers will be furnished to discuss the vipsy-
moth problem at farmers’ institutes.

In the spring of 1914 a colored poster was prepared showing the
life histories of the gipsy moth and the brown-tail moth and several
of the introduced natural enemies. These posters have been dis-
tributed to all the post offices in the infested district, to granges,
libraries, and educational institutions. Reproductions from this poster
have been made in the form of post cards and distributed to schools
and parties interested in the work.

During October, 1914, an exhibit covering the gipsy-moth work
of the bureau was made at the Boston Pure Food and Domestic
Science Exposition, as a part of the Government exhibit. Living
parasites were on exhibition as well as mounted specimens and other
information.

Efforts are continually being made to advise property owners
concerning-the methods which should be taken by them to prevent
serious Same to their trees, and good results are being accom-
plished along these lines.

CONCLUSION.

The gipsy-moth work of the Bureau of Entomology is well organ-
ized and each section is accomplishing good results.

The scouting work and the quarantine work are doing efficient
service and preventing the spread of the gipsy moth, but on account
of the enormous area which is infested it is impossible to cover much
of the woodland. This has resulted in a gradual spread of the insect.
It has been possible to restrict this spread very materially toward
the westward.

The work of natural enemies, including the parasites, predacious
enemies, and disease, have helped materially im decreasing the
amount of infestation, and it seems probable that these influences
will become more potent factors in the future.

The importance of bringing forest lands into a erowth which is
unfavorable to the development of the gipsy moth can not be too
strongly urged, as the work of natural enemies is likely to fluctuate _
from year to year on account of adverse conditions or the decimation ©
of the beneficial species by other parasitic forms. Every movement
toward bringing about more unfavorable forest Brewele is therefore a
step in ane the gipsy-moth problem. |

WASHINGTON : GOVERNMENT PRINTING OFFICE: 1915