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CIRCULAR No. 464 MARCH 1938
UNITED STATES DEPARTMENT OF AGRICULTURE
WASHINGTON, D.C.
THE GYPSY AND BROWN-TAIL MOTHS AND THEIR
CONTROL’
By A. F. Buresss, principal entomologist, Division of Gypsy Moth and Brown-Tail
Moth Control, and W. L. Baker, assistant entomologist, Division of Forest Insect
Investigations, Bureau of Entomology and Plant Quarantine
CONTENTS
: Page Page
RhewypsSyeMoOpnes === eee ee ee oe 1 | The brown-tail moth—Continued.
History of the pest in the United States____ 1 INative:ecnemies 222 sa een eee see 33
Conditions of infestation in New England.. 5 Introduced parasites and other enemies_____ 33
IP ORIS COT Yee ee eee eee se 6 | Effect of low temperatures__-_---_.----______ 33
Injury caused by the gypsy moth__________ 8 Methodsiof control at eat eae set eo es 33
WOOGRD aN USE ee en ee es ga 9 Recent Controle lontsess eee 3
Wieansiotspread =.) ee itia Leeehie 13 | Organization and status of work against the
HnecholiGlimates———=— = SP 14 gypsy moth and the brown-tail moth________ 34
INGLIVOlCNeMieS © acs en eer eo on ye ee ee 15 VA TING os oe ae oe ra Re ee tee 34
Introduced parasites and other enemies______ 15 INeweklampshires]: Gas sae eee eta 35
@ontrolemet hogs asses ee ee ae 16 GTI TG xe a eee ee 35
Recent control work in New England and iViassachusetis=eae = sas 2 hee eee eee ee 35
ING wry ork woodlands: =-25 2-225 2. 23 IRhodewslandis=== 2 ee eee 36
Record of clean-up of outlying colonies______ 23 Connechicu te. eras a eee ee eee 36
Extermination project in New Jersey______-_ 25 ING WSY(Or Koka eee eet eae pons Se 2 ay tens 3 36
Extermination project in Pennsylvania_____ 28 IN CAS CTSC Vissi Sate 8 a le oe 36
HHetbrowal-vallomno thee ete See ee eee EEE 29 IRennSylvariiaeee eee. eee eee eek eee 36
History of the pest in the United States____ 29 Mominioniok@anaday _-—- = i eee 36
STOUR ISL OG Vee oe ee ee Oe eee 31 United States Department of Agriculture... 37
Hoodsplants aaa ee eee eee Per ee 31 Cooperative: workers oh ss setae Seas ees 37
Injury caused by the brown-tail moth______ 32
THE GYPSY MOTH
HISTORY OF THE PEST IN THE UNITED STATES
In 1869 a number of egg clusters of the gypsy moth (Porthetria
dispar Li.) were brought from France to Medford, Mass., by a French
mathematician and astronomer, who had the idea that he could cross
this insect with silkworm moths and thus develop a hardy race of
silk-producing insects. In the course of his rearing experiments some
of the eggs were accidentally lost or some of the caterpillars escaped,
and he made at that time public acknowledgment of this fact, evidently
appreciating the danger.
The insect increased slowly at first. After 10 years it seemed to
have been noticed by local residents but was believed to be some
native caterpillar. Not until the summer of 1889, or 20 years after
its introduction, did this insect become so abundant and destructive
as to bring it into general public notice. At that time fruit and
shade trees were completely defoliated, and the caterpillars, swarming
1This circular supersedes Farmers’ Bulletin 1623, The Gipsy Moth and the Brown-Tail Moth.
35349°—38——1 1
2 CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
into the houses, became a very grave nuisance. The situation was
so serious that the State of Massachusetts appropriated funds and
delegated to the State Department of Agriculture the task of exter-
minating this pest.
The infested area then covered about 359 square miles, and trees
in many towns around Boston were completely defoliated each season
fora number of years. As the work continued, more effective methods
of treatment were developed and better results were obtained; conse-
quently, during the summers of 1898 and 1899 little defoliation could
be found in the entire area and few specimens of the moth were located
throughout the residential sections. Careful examination indicated
that the insect had been exterminated in some of the towns bordering
the originally infested area. In February 1900 the legislature ordered
the work discontinued because of the popular belief that the danger
had passed, in spite of the advice of experts that the insect had not
been stamped out.
During the next 5 years the insect increased enormously. Many of
the towns and cities in the old infested area were overrun with cater-
pillars, which completely defoliated trees in many of the residential
sections, and thousands of acres of woodland were stripped of leaves
during the summer. The situation became so serious and intolerable
that in 1905 the State resumed control work. In the meantime the
insect had spread far beyond the original limits of infestation, more
than 2,224 square miles being involved in Massachusetts as well as
many isolated areas in Maine, New Hampshire, and Rhode Island.
In 1906 an appropriation was made by Congress, and the Secretary
of Agriculture was authorized to take all possible measures, in coopera-
tion with the States concerned, to prevent the spread of this pest.
The insect had increased to such enormous numbers and had spread
so rapidly that the utmost efforts of the Federal and State forces
were only able to apply relief measures in the badly infested residential
sections and slightly retard the continued spread of the pest. Efforts
were made to prevent the shipment of the insect to uninfested localities
by inspecting products that were likely to carry it. This phase of
the work was greatly strengthened as a result of the enactment of
the plant quarantine law by Congress on August 20, 1912. Since
October of that year shipments from the infested district have been
regulated by Federal quarantine.
On account of the continued spread and increasing damage caused
by this insect, efforts were constantly being made to develop better
means of control. The process of manufacturing lead arsenate, which
was first made and used on the gypsy moth work in 1893, was im-
proved so that the cost of production was reduced and the product
could be more effectively applied. Spraying machinery and equip-
ment were developed to a high point of efficiency. The details of
field management were constantly improved, following experimental
work in carrying on field operations, in order that the greatest possible
volume of effective work could be done with the funds available.
In spite of the efforts that were made by the Federal Government
and all the States concerned, the insect continued to spread. By
1914 it had covered the southern half of New Hampshire and extended
as far east as Bangor, Maine. On the west it had crossed the Con-
necticut River in Massachusetts and into Vermont. Rhode Island
and towns in eastern Connecticut were found to be infested.
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 3
During the war period conditions were unfavorable for preventing
spread. The loss of efficient personnel and the constant turn-over of
men, together with extraordinary increase in costs, made progress
difficult. By the fall of 1922 scattered colonies were found farther
west in Vermont, Massachusetts, and Connecticut, and in New York
State near the Massachusetts State line. There was every indication
of the continued spread of the insect unless more intensive work
was done.
To meet this serious situation a conference was held in the office
of the commissioner of farms and markets in Albany, November 26,
1922, which was attended by representatives from all the infested
States, the Dominion of Canada, and the United States Department
of Agriculture.? The entire subject of the prevention of spread of
the gypsy moth and its control was discussed, and a resolution was
adopted urging that sufficient funds be obtained from the States
interested and the Federal Government to continue and strengthen
control methods in the infested area, to do necessary scouting for the
discovery and destruction of border infestations, to determine the
location of the most practical place for a control zone, to take necessary
steps to make control therein effective, and to destroy all infestations
in and west of said zone.
To carry out this project, in April 1923 the State of New York
appropriated $150,000 to be administered by the Department of
Conservation. Federal funds were also provided for the fiscal year
beginning July 1, 1923, to bring about effective cooperation.
The plan finally adopted, by the Federal and State authorities, was
to locate a zone where clean-up operations to prevent westward
spread of this pest would be centered. This barrier zone embraced
an area of about 9,000 square miles east of the Hudson River extend-
ing from Long Island Sound (excluding Westchester County, N. Y.)
to the Canadian border, a distance of more than 250 miles, and rang-
ing in width from 25 to 30 miles (fig. 1). This is the shortest and
most feasible area in the United States that could be selected to pre-
vent Nation-wide spread of the insect. The territory east of this
zone was to be treated by the States concerned as far as their funds
would permit, and their work was to be supplemented by liberation
of imported parasites and other natural enemies of the insect by the
Bureau of Entomology. Work in the New York portion of the area
was to be financed by the State, with such assistance as could be given
by the Bureau after covering the eastern part of the zone in western
Vermont, Massachusetts, and Connecticut.
_ While much of the extremely rugged country in the Adirondacks
in northern New York and the Green Mountains in Vermont was
avoided, as well as the Catskills and some of the rougher country
west of the Connecticut River in Connecticut, there are areas in this
zone, embracing the Berkshire Hills in western Massachusetts and
some of the territory directly south and southwest of them in Con-
necticut and New York, where the terrain is extremely difficult.
In 1924, owing to the number of infestations found in Massa-
chusetts and Vermont, and the discovery of a colony at Henrysburg,
Quebec, by the inspection force of the Dominion entomologist of
Canada, the quarantine line was moved westward from the eastern
2 FELT, E. P., and others. THE GYPSY MOTH, AN IMMINENT MENACE TO THE FOREST AND SHADE TREES
OF THE STATE OF NEW YORK. N. Y. State Dept. Farms and Markets Agr. Bull. 148, 58 pp., illus. 1922.
4 CIRCULAR 464, U. 5. DEPARTMENT OF AGRICULTURE
boundary of the zone to embrace the entire State of Vermont and
additional towns in northwestern Connecticut. A foreign quaran-
tine regulating the movement of Christmas trees was made effective
covering the southern tier of towns in the Province of Quebec. In
1926, owing to the effectiveness of the clean-up work in the zone and
the fact that scouting west of the zone showed no infestation, the
area under quarantine lying in the zone was eliminated from quaran-
tine. The Canadian quarantine was withdrawn July 1, 1928.
LEGEND
AREA QUARANTINED FOR GYPSY MOTH 1934.
DELIMITS AREA QUARANTINED FOR BROWN-TAIL MOTH 1934.
E35 sarrier Zone.
AREA REMOVED FROM BARRIER ZONE 1934.
PENN, GYPSY MOTH INFESTED AREA.
ISOLATED GYPSY MOTH
INFESTATIONS IN NJ. AND N.Y.
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SATLANTIC
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FIGURE 1.—Barrier zone and status of the gypsy moth and brown-tail moth control areas at the end of 1934.
Later in 1928 more infestations were found in the Massachusetts
and northern Connecticut portions of the barrier zone than during
the previous fiscal year. This made the problem far more difficult
and emphasized the necessity of carrying on work in the territory
east of the zone to facilitate eradication in the zone itself. Since
there was also an increase in infestation directly east of the zone,
7 towns in Vermont, 12 in Massachusetts, and 31 in Connecticut,
embracing an area of 1,581 square miles, were reclassified from the
lightly infested: to the generally infested area.
-
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL oO
Scouting during the latter half of 1929 and the first half of 1930
showed a further increase in the number of infestations in the barrier
zone, and Congress made additional funds available for clean-up
work. No provision was made, however, for examination of terri-
tory immediately east of the zone to check the increase there. The
infestations located in 1929 and 1930 were new ones, as most of those
previously discovered had been cleaned up.
In 1933, after the passage of the National Industrial Recovery Act,
funds were made available and extensive scouting and clean-up work
was undertaken between the barrier zone and the Connecticut River.
This was extended very materially by personnel from certain Civilian
Conservation Corps camps, which were supervised by the gypsy moth
organization of the Bureau of Entomology and Plant Quarantine
through cooperative arrangements with the Forest Service of the
United States Department of Agriculture, the State forest services,
and the United States Department of the Interior.
The prompt elimination of a few sporadic colonies that had been
found just beyond the zone, together with the suitability of the area
in the zone for effective clean-up, offers conclusive proof of the feas-
ibility of checking westward spread.
In 1934 a change in quarantine was made by transferring from the
lightly to the generally infested area 74 towns in Maine, 5 in New
Hampshire, 2 in Vermont, and 3 in Connecticut. In northern Ver-
mont 39 towns were dropped from quarantine. The barrier zone
line in northeastern New York was relocated on the New York-
Vermont State line, thus eliminating 807 square miles, and a strip of
towns in Vermont adjoining the barrier zone on the east, aggregating
604 square miles, was added to the zone.
Since July 1935 emergency funds have been made available for
gypsy moth work, and more scouting and clean-up work has been
carried on than heretofore. This has suppressed the insect in many
isolated colonies and improved the condition in the barrier zone and
the area adjoining it to the east.
CONDITIONS OF INFESTATION IN NEW ENGLAND
From the beginning of its gypsy moth work the Bureau of Ento-
mology obtained general records of the density of local and general
infestations in the territory not covered by the Bureau. Since 1911,
however, counts of egg clusters have been taken annually from a
series of woodland plots in the eastern portion of the infested area.
They are summarized as follows:
Egg clusters
Egg clusters
per acre Year per acre
“ar LS Sa A gt a a A era 431) | Oe ee Ronn nee ee est FF ST 110
Ps LASS 3? SESS * ieee oe ee PEPE Les J HR Gal: VOR TOSI fete lit 50
Lis 3 Geek See Oa es eC BYon pale) agile Deke ee ee oe ee ee 61
Lee eS Sa oe a ee STR 2 ee ees 127
Lie 22k toa a es AAO OMe ee ge 303
Te De 2 ee eh NR a i ipl Sel ha eee ee tee Cte 722
Va wee eee Br TAN PAN OS! 2 407
LS iets Se i ry ee Be j4 PeC ayy AUS). ce ee 66
LSU oS ee EM Ses el pe ee SS Sk ey 42
i AD aR aed Scat Tee a a Fee eats Ro tile Oil Ne Si 112
LSet | Ue ils oe eG eS Dots | LO ae ene CVC set 344
Hera pen mene ty); rl) _phiechogh cen 402 | 1934 181
6 CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
As the habits and the variable mortality of the gypsy moth and its
food-plant limitations cause wide differences in its abundance in
various parts of the infested area, it has seemed that the damage done
and the possibilities of greatest "future injury could be gaged most
accurately by determining the defoliation caused by the species over
the area as a whole. The total acreage showing from 25- to 100-per-
cent defoliation each year beginning in 1924, when defoliation was less
than in any previous year, is as follows:
Year Acres defoliated | Year Acres defoliated
19242 Lioisa8 On iS EN S25MOS1. Oe wee I ee erie 204, 720
FIGURE 2.—Life stages of the gypsy moth: A, Female moth; B and F, pupae; C, larvae or caterpillars;
D, male moth; E, egg mass. All about three-fourths natural size.
The danger of reinfestation of the barrier zone depends largely on
the severity of infestation east of the zone. In the last 3 years the
areas of defoliation were smaller in eastern Massachusetts and certain
sections of southeastern New Hampshire, which comprise most of the
older infested territory. In the same years heavy defoliation was
noted much farther west in Massachusetts, and in 1934 and 1935
extensive areas of complete defoliation occurred in the Connecticut
River Valley and the adjoining territory about 20 miles from the zone.
LIFE HISTORY
The gypsy moth passes through four stages—the egg, the larva or
caterpillar, the pupa, and the adult or moth (fig. 2). There is one
generation a year. The times of the year when the different forms
may be found in the field are shown in figure 3.
(
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 7
THE EGGS
The female gypsy moth lays from 100 to 800 eggs in a cluster,
depending on her size. The average number per cluster is approx-
imately 400. In light infestations where the food supply is plentiful
clusters are larger than the average, and in heavy infestations where
the food supply becomes limited during the late larval stages they
are smaller. Each cluster is covered with buff-colored hairs from
the body of the female, which no doubt serve as a protection for the
eggs during the long interval between oviposition and hatching.
Most of the egg clusters are laid in July and hatch the following
spring. The hatching date varies from about May 1 in southern
New England to May 25 in the extreme northern part. The date
of oviposition bears no relation to the date of hatching, as eggs laid
in mid-August may hatch at the same time as those laid early in July
under the same envi-
ronmental conditions.
Eggs deposited in warm
locations, as on the
southern exposure of
buildings, may hatch
several days earlier than
others laid in cool and
moist locations.
The gypsy moth egg
must be exposed to a
chillng temperature
before it will hatch.
Just what this temper-
ature is is unknown.
Eges that have under-
gone this conditioning
process will hatch in
midwinter in a warm
building.
The female moth de- ;
posits her ego clusters FIGURE ee ees Seat ene ner stages of the
on the trunks of trees,
on the underside of limbs, under loose bark, in cavities in the trunks
or branches, and sometimes on leaves, on ground debris, under stones,
and in stone walls. When infested trees are found along stone walls,
a large proportion of the eggs are often laid in the wall; but where
the ground is free of stones or debris, a large proportion of clusters
will be found on the tree trunks.
THE LARVAE
The newly hatched larvae begin immediately to search for palatable
food. In pure stands of favored food this is a simple matter, but as
the proportion of favored food in the stand decreases the problem
becomes more acute. There is no evidence that such larvae can pick
out a favored tree from an unfavored one without examining the
foliage. They find the food through random movement. The
normal mortality of first-stage larvae is very high. Newly hatched
larvae can ordinarily live only about a week without feeding. The
re) CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
absence of water becomes less of a problem as the larvae increase
in size, probably because of the decrease in the ratio between evapo-
rative surface and body volume.
First-instar larvae move very slowly. They are active only when
the temperature is above 60° F. and are more active when the temper-
ature is 70° or higher.
Gypsy moth larvae that are to become male moths molt five times,
and those that are to be females molt six times. The full-grown
larva is from 1% to 2% inches long. The head has yellow markings;
the body is ale or ‘sooty colored, hairy, and on the dorsum is a
double row of five pairs of blue spots followed by a double row of six
pairs of red spots. As the larvae grow, the quantity of foliage eaten
per day increases tremendously. Approximately 75 percent of all
the foliage eaten by larvae having five instars is eaten in the fifth
or last instar, and approximately 65 percent of the foliage eaten by
larvae living through six instars 1s consumed in the last instar. Con-
trol measures against larvae should therefore be applied as soon as
possible after the eggs hatch, to protect the foliage from the later
instars.
THE PUPAE
When full grown, the larvae shed their skins and transform to
chestnut-brown pupae bearing tufts of yellow hairs. After about 10
days in this stage the adult moths emerge.
THE ADULTS
The male gypsy moth is dark brown with black wing markings,
and is a strong flier. The males usually emerge earlier than the
females, and fly near the ground, in a characteristic zigzag manner,
in search of female moths.
The female moth is nearly white, with black wing markings, and
is much larger than the male. Because of the weight of their bodies,
the females are incapable of flight, and are usually found beside their
empty pupal cases. Here they deposit their eggs, and once this
function has been performed they die. Oviposition begins within a
day or two after the female emerges from the pupa. The moths do
not feed.
INJURY CAUSED BY THE GYPSY MOTH
It is impossible to state with precision the loss to New England
forests due to the ravages of the gypsy moth. The best information
compiled from data extending over a long period of years indicates
losses of many millions of dollars in tree growth. These losses have
been due not only to the direct or indirect killing of the trees but
also to the retardation of growth through defoliation. Although far
less spectacular than the immediate killing of trees, the second type
of loss is more to be feared, for tens of thousands of trees are so
affected for every one killed. Most conifers, notably hemlock and
white pine, are killed by a single complete defoliation. Most rapid-
growing deciduous trees put out a new crop of foliage the same season
in which stripping occurs; they are therefore without foliage but a
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 9
short interval during the growing season, but retardation of growth
aud less wood result.
Trees that are weakened by defoliation are susceptible to secondary
injuries by fungi and bark borers. From 1912 to 1915 heavy mor-
tality was noted among oaks that had been defoliated by the gypsy
moth, and this was followed by an outbreak of the two-lined chestnut
borer (Agrilus bilineatus Weber), whose larvae fed beneath the bark
of the weakened trees. During recent years this beetle has not caused
noticeable damage, but such a condition might recur without warning.
The importance of tree growth in aiding retention of moisture in
the soil and preventing erosion, particularly in rugged country, is
well recognized. Defoliation encourages evaporation of moisture
from the soil during the most critical growing period in the summer,
renders such areas more susceptible to forest fires, and undoubtedly
diminishes the flow of small streams, some of which furnish the water
supply for reservoirs maintained for commercial or city use. The
money value of these losses cannot be readily computed.
Defoliated or dying trees along roadsides and streets in residential
areas are objectionable, and the removal of trees from such locations
is a distinct loss to the community and the publicin general. Recrea-
tional areas are being used to a greater extent each year, and here
the value of trees far outweighs the commercial value of the timber.
Ragged foliage and denuded trees, accompanied by crawling cater-
pillars, are avoided by the public. Trees in such locations have more
of a struggle for existence than trees that grow in natural environ-
ment without interference by man, and they therefore require added
protection. The increased interest in natural playground develop-
ment in New England and New York State seems to warrant more
than ordinary expenditures to preserve the trees for their esthetic
value alone.
Figures 4, 5, and 6 illustrate the results of gypsy moth feeding in
various types of stands.
FOOD PLANTS
Unlike many leaf-eating insects, which confine their feeding to a
single species or group of plants, the gypsy moth is a general feeder
on trees and shrubs. In fact, in heavy infestations few species of
trees are ignored, especially by the larger larvae, and when food is
scarce grass and cultivated crops are sometimes eaten.
A study of the food plants of the gypsy moth in 1913 ® revealed
distinct differences in the preferences of the very small and the larger
larvae. The food plants were grouped in four classes, which are
given herewith, with a few changes that subsequent observations have
justified. This classification can be used as a basis for thinning to
eliminate the most favored species and retain and encourage the more
valuable and resistant species. It will be noted that class 2 includes
most of the conifers, which suffer severely if grown in association with
more favored species. Unfortunately, the infested region abounds
in class 1 trees either in solid stands or in more or less diluted mixtures.
ie MOSHER, F.H. FOOD PLANTS OF THE GIPSY MOTHIN AMERICA. U.S. Dept. Agr. Bull. 250, 39 pp., illus.
1915.
35349°—38——2
CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
10
illed by the gypsy moth.
ted and k
la
defoli
ith favored food trees,
ture Ww
1X
inm
ine growing i
FIGURE 4.— White p
ted by the gypsy moth.
la
Oak trees defoli
RE 5.
FIGU
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL Lit.
FIGURE 6.—Hemlock growing in mixture with favored species defoliated and killed by the gypsy moth at
Orange, Mass., in 1934.
12 CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
Cuass 1.—Species that are favored food for the gypsy moth larvae
Alder, speckled Oak, rock chestnut
Apple Oak, bear
Aspen, American ~ Oak, bur
Aspen, large-toothed Oak, pin
Balm-of-Gilead Oak, post
Birch, gray Oak, red
Birch, paper Oak, scarlet
Birch, red Oak, shingle
Blueberry (Vaccinium angustifolium) Oak, swamp white
Boxelder Oak, white
Gum, red Poplar, Lombardy
Hawthorn Rose, pasture
Hazelnut Serviceberry
Hazelnut, beaked Spruce, blue?
Larch, American Sumac, mountain
Larch, European Sumac, scarlet
Linden, American Sumac, staghorn
Linden, European Willow, glaucous
Mountain-ash Willow, sandbar
Oak, black Willow, white
Oak, dwarf chestnut Witch-hazel
Cuiass 2.—Species that are favored food for the gypsy moth after the earlier larval
stages
Beech, American (1)4 Pine, western white
Cedar, red (4) Pine, white
Chestnut Plum, beach
Hemlock Spruce, black
Pine, jack Spruce, Norway
Pine, pitch Spruce, red
Pine, red - Spruce, white
Pine, Scotch
Cuiass 3.—Species that are not favored but upon which a small proportion of the
gypsy moth larvae may develop
Barberry, European Elm, slippery
Bayberry Gum, black
Birch, black Hickory, bitternut
Birch, yellow Hickory, mockernut
Blueberry, low Hickory, pignut
Blueberry, tall Hickory, shagbark
Butternut (4) i hie Hophornbeam
Cedar, southern white (4) Hornbeam, American
Cherry, sweet Maple, Norway
Cherry, wild black Maple, red
Cherry, wild red - Maple, silver
Chokeberry Maple, sugar
Chokecherry Pear
Cottonwood ; Poplar, silver.
Cranberry, American Sassafras
Elm, American Sweetfern
Elm, European Sweetgale
4 Numbers in parentheses refer to the original classification of plants that have been reclassified. Blue (fea
spruce has been subsequently added. bi
GYPSY AND BROWN-TAIL
MOTHS AND THEIR CONTROL
Cuass 4.—Species that are wnfavored food for gypsy moth larvae
Arborvitae
Arrowwood
Arrowwood, maple-leaved
Ash, black
Ash, blue
Ash, red
Ash, white
Azalea, white and flame
Balsam, fir
Blackberry, high
Blueflag, larger
Catalpa, hardy
Cornus
Cranberry tree
Currant, red
Cypress, bald
Dangleberry
Dock, narrow
Dogwood, flowering
Elder, American
Eubotrys, swamp
Feverbush F
Grape
Greenbrier
Hackberry
Hardhack, pink
Hardhack, white
Holly, American
Honeylocust
Honeysuckle, bush
Huckleberry, highbush
Inkberry
Juniper, common
Kentucky coffeetree
Lambkill (sheep laurel)
Locust, black
Maple, mountain
Maple, striped
Mountain-laurel
Mulberry, red
Mulberry, white
Osage-orange
Osier, red
Pepperbush
Persimmon
Poison-ivy
Privet
Raspberry
Sarsaparilla
Skunkeabbage
Spicebush
Sweetbrier
Sweet pepperbush
Sycamore
Tea, Appalachian
Tuliptree
Viburnum, sweet
Walnut, black
Willow, bay-leaved
Winterberry, smooth
13
MEANS OF SPREAD
Egg clusters of the gypsy moth deposited on trees, lumber, stone,
and other products that are likely to be shipped may be carried long
distances and cause new colonies of the insect to be established. The
only way to prevent spread of this kind is to inspect such products and
treat any clusters found on them before they are shipped.
Larvae of the gypsy moth may be carried on such moving objects
as trains and automobiles. Horse-drawn vehicles and freshets may
also transport them for limited distances, and egg clusters on debris
may be carried by high water. The danger of such spread is depend-
ent upon the extent of infestation along railroads, highways, and
streams. | :
It is probable that the principal agent in the spread of the gypsy
moth is the wind. The chief trend of spread of the insect, since its
introduction into New England, has been to the north and northeast,
which is the general direction of prevailing surface winds after the
hatching season.
Since the newly hatched larvae are abundantly supplied with hairs,
they are easily carried by the wind. Probably few larvae are ever
blown loose from their supports by the wind. An enormous number,
however, spin down from tree tops when disturbed and are intercepted
by air currents; the strand of silk is broken and they are whirled away
with this silk attached to their bodies. Spinning larvae normally
sever the strand of silk by biting only when they come to rest upon
some object; they seldom do this while hanging free. The distance
that a larva may be carried aloft by currents of air depends to some
14 CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
extent upon the length of silk attached to its body. Larvae have
been captured onscreens more than 20 miles from the nearest known
infestation, and one larva has been taken on a screen attached to an
airplane at a height of about 1,800 or 1,900 feet above the ground
(2,000 feet above sea level). The height to which they may be carried
varies from day to day and may greatly exceed 2,000 feet. Once lar-
vae have reached such heights, they may encounter cross currents of
air and be blown in the direction opposite to which surface winds are
blowing.
Transportation of larvae by the wind is, however, less serious than
it would appear. The farther the larvae are carried the more widely
they are separated and the less chance they have of falling close
enough together to establish infestations. ‘There must be a large
number of such larvae present to offset natural mortality. Millions
of larvae, however, may be blown out of an infestation, fall nearby,
and succeed in spreading the infestation short distances. That
undoubtedly is why the infestation in New England has progressed
only a few miles per year. Were it not for the tremendous natural
mortality of larvae, the insect would have become established in new
localities far more rapidly than it has. For this reason special efforts
are made to destroy egg clusters before hatching, particularly those
that are in exposed or wind-swept locations.
Wind spread takes place primarily on hot days when convection
currents from the heated surface of the ground are prevalent. The
appearance of cumulus clouds signifies the existence of convection
currents and the days when danger of wind spread is greatest.
EFFECT OF CLIMATE
The effect of climate, in all its phases, upon the gypsy moth has
never been fully investigated, and is therefore little understood. The
effect of extremely low temperatures upon overwintering eggs has
received more study than any other single factor. It has been deter-
mined that all egg clusters are killed when exposed to a temperature
of —25° F. and that some eggs are killed at —15°.
In the field, however, temperatures fluctuate greatly within very
short distances. For instance, a temperature of —25° F. at a weather
station in a town or city does not necessarily mean that such a tem-
perature is common to the entire town. For this reason it has been
impossible to estimate accurately just what was happening to gypsy
moth eggs in towns from which temperature records were available.
Winter temperature is an important factor in gypsy moth abund-
ance in most of New England. In some winters the temperature
does not get low enough to be fatal, but in other years mortality
from this cause is heavy. In northern Maine, northern New:iHamp-
shire, and most of Vermont except the Champlain and Connecticut
River Valleys, minimum winter temperatures are low enough to kill
ege clusters that are not protected by snow, ice, or otherwise, and in
most of these areas infestations have become established slowly and.
the increase of the species has been retarded.
Late frosts in the spring sometimes cause severe damage to foliage,
and this usually results in heavy mortality of the small larvae. This
is most likely to occur locally, but was noticeable in many sections
of the infested areas during the spring of 1936. Frequently there is
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 15
also a considerable mortality of newly hatched larvae during long
periods of rainy weather accompanied by low temperatures.
Evaporation is another climatic factor that is known to influence
caterpillar activity. Feeding is noticeably greater when evaporation
is high, the loss of water from the caterpillar’s body probably acting
as the stimulus. This may account for the more rapid feeding in the
upper part of the crown than in the lower part. Such feeding serves
to open the crown canopy, admitting more light, raising the tempera-
ture, permitting a freer circulation of air, and increasing the evapora-
tion rate below. Thus the entire crown becomes more and more
susceptible to rapid feeding. Young larvae seem to be attracted and
older larvae repelled by strong light.
NATIVE ENEMIES
No insect enemies of the gypsy moth native to New England cause
any noticeable reduction in its numbers. This is shown by the fact
that from 1900 to 1905, when no systematic effort was made to sup-
press the insect, alarming i injury resulted, and native insect enemies
did not increase to any marked degree. ‘The same is true of native
insect-eating birds. While they undoubtedly feed to seme extent on
gypsy moth caterpillars, there is no record of their being able to control
the insect. The “wilt,” a disease that attacks and kills the cater-
pillars and pupae, has probably occurred in this country for many
years. During some seasons it kills an enormous number of the
caterpillars and is often an important factor in reducing the infesta-
tion locally. As a rule this disease is more common in heavy infesta-
tions, although many caterpillars have been killed by it when the
infestation has been relatively light.
INTRODUCED PARASITES AND OTHER ENEMIES
In 1905 the State of Massachusetts, in cooperation with the Bureau
of Entomology, began to introduce parasites and other natural enemies
of the gypsy moth from its native home in Europe and Japan. Since
that time a large quantity of parasitized material has been received,
and as a result some important natural enemies have become estab-
lished in this country and are assisting in the control of the pest.
The enemies which have become established, and which destroy the
largest number of gypsy moth caterpillars and pupae, are the beetle
Calosoma sycophanta L.; two species of parasitic flies, Sturmia scutellata
R. D. and Compsilura concinnata Meig., one of which attacks the
caterpillars of the brown-tail moth as well as those of many native
insects; and a small wasplike fly, Apanteles melanoscelus Ratz. Two
tiny important parasites of gypsy moth eggs have also been estab-
lished, one, Oencyrtus kuvanae How., having been introduced from
Japan and the other, Anastatus disparis Ruschka, from Europe and
Japan. Two other introduced parasites, Hyposoter disparis Vier.
and Phorocera agilis R. D., are established in this country, but they
have not increased sufficiently to be important factors in gypsy
moth control.
The work of the natural enemies of the gypsy moth has greatly
reduced the numbers of the insect. In some sections the reduction
has been greater than in others, and their effectiveness has also varied
from year to year.
16 CIRCULAR 464, U. 8S. DEPARTMENT OF AGRICULTURE
Since 1911 annual examinations have been made at observation
points scattered over the infested area to determine the intensity of
the infestation and the percentage of eggs, larvae, and pupae killed
by introduced natural enemies. These points were located in York
County in southwestern Maine; in Strafford, Merrimac, Hillsboro,
and Rockingham Counties in southeastern New Hampshire; and in
Essex, Middlesex, Worcester, Norfolk, and Plymouth Counties in
eastern Massachusetts. The results indicated a rapid building up
of the natural enemies, with an increasing percentage of the eggs,
larvae, and pupae being destroyed, until 1923. In the meantime the
intensity of the gypsy moth infestation, which had already reached
a high level in 1912, remained high until 1921, when it declined
rapidly until 1924. Since then there have been fluctuations in both
the intensity of the infestation and the percentage of moths destroyed,
but since the natural enemies have become thoroughly established
the infestation has not reached the high level attained in the earlier
years in some portions of the area. To evaluate correctly the benefit
derived from parasites and natural enemies, other factors, including
climatic conditions, must be taken into consideration. Without
doubt, however, these beneficial insects have played a useful role
with other control agencies in decreasing damage by this pest.
CONTROL METHODS
GENERAL METHODS
A number of standard methods are in use for controlling the gypsy
moth. They may be applied singly or in combination, depending on
the tree growth, the density of infestation, and other local conditions.
The essential information concerning each method is given in the
following paragraphs, but each owner or operator should select the
procedure that will give the best results when applied to his particular
problem.
USE OF GYPSY MOTH CREOSOTE
The application of gypsy moth creosote with a brush will destroy
ege clusters without removing them from the trees or objects on which
they are deposited. This work can be done between the first of
August and the time of hatching in the spring, which is about the
first of May. ‘Treatment can be given most satisfactorily when there
is no snow on the ground.
Gypsy moth creosote is on sale in the infested area and is a low-
grade coal-tar creosote which has been impregnated with sufficient
coal-tar pitch to discolor the egg masses and thus indicate those that
have been treated. A satisfactory grade can be bought in quantity
under the following specifications:
Specificporayity sea) - ee) ees ie 4. . ie ae Beets 0.990—-1.025 at 15.5° C.
ParSaC Gs es Se ere ee 10 to 15 percent.
Coaletar iby drocarponses 2 =. sang ee 80 to 85 percent.
Water-anotrmoresuhan 2eee ie: 2h) - Se ee eee 2 percent.
Flasht point = Preheat s genie iiiei tet |. 5 ee OR eee 70°—75° C.
No separation of naphthalene at 0° C. -
Initial boiling point, 170°—180° C.; 95 percent over at
285°—295° C.
In addition, not less than 6.5 percent nor more than 8.5 percent by
weight of coal-tar pitch shall be added to the creosote furnished under
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 17
this specification, in order that the finished product shall bave a color
suitable for the proper staining of gypsy moth egg masses. This
material must remain fluid and workable at subzero temperatures.
USE OF BURLAP BANDS
Gypsy moth caterpillars usually seek shelter during hot, sunny
days, and if a band of burlap is attached to a tree (fig. 7) large numbers
FIGURE 7.—Burlap band on tree showing caterpillars beneath.
of them will crawl beneath it, where they may be crushed each day.
A strip of burlap about 8 inches wide is placed loosely around the tree
trunk, and a piece of twine is passed around the center and_tied to
hold it in place. The top part of the burlap is then folded down to
make a double shelter beneath it.
This method requires considerable hand labor, but is effective in
many places. If brown-tail moth caterpillars are present on the
35349 °-—38——_3
18 CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
trees, burlap should not be ap-
plied until after June 15, when
most of these caterpillars have
pupated. Otherwise they may
form their cocoons beneath it,
and the workmen may be poi-
soned by the poisonous hairs
that accumulate there.
USE OF STICKY BANDS
Bands of sticky tree-banding
material, which may be obtained
on the market, may be used on
tree trunks (fig. 8) after the bark
has been scraped so that the
material can be applied evenly
in a thin layer with a paddle.
These bands prevent caterpillars
from ascending the trees, and if
proper treatment of egg clusters
has reduced the number of lar-
vae sufficiently, this is a very
effective measure. Further-
more, as the caterpillars are
usually massed in large numbers
beneath the bands, conditions
are favorable for wilt disease to
develop, and the caterpillars
often die in large numbers from
this disease and from starva-
tion. Every week or 10 days
during the caterpillar season a
comb or similar implement
should be run over the band to
keep the surface from harden-
ing and to bring up fresh, sticky
material from the part near the
bark. This material is expen-
sive, and considerable labor is
required to prepare the trees
and apply and tend the bands.
In some locations, particularly
where there has been a heavy
deposit of egg clusters on debris
on the ground or in stone walls,
FIGURE Sea imunk below its use is advisable.
USE OF GYPSY MOTH TREE-BANDING MATERIAL
A black greasy substance called “gypsy moth tree-banding material”
is sometimes used to prevent caterpillars from crawling up the trunks
of trees. It is similar to the product known as ‘‘Raupenleim” that
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 19
has been used in German forests for many years. It has to be applied
with a special gun in a thick narrow band encircling the tree trunk.
At the present time it is not manufactured in this country, but infor-
mation concerning its preparation and use can be sopalicdl by the
Greenfield, Mass., office of the Bureau of Entomology and Plant
Quarantine.
SPRAYING
The most effective spray material is lead arsenate. To make it
adhere firmly to the foliage 4 fluid ounces of fish oil or raw linseed oil
should be placed in the spray tank for each pound of lead arsenate.
The oil should be added after the poison is well mixed with water in the
tank, and while the whole is being agitated. Agitation should be con-
tinued while the spray is being applied. The best grade of fish oil,
known as ‘light pressed,’’ should be used. Five pounds of lead
arsenate to each 100 gallons of spray is required to kill larvae that are
half grown. A slight reduction in dosage may be made for the smaller
larvae. In areas where there is mixed growth it is impractical to
begin the spraying until the trees that produce foliage the latest—and
they are usually the oaks—are ready for treatment. Under such
circumstances larvae are found in several stages of development, and
use of the stronger dosage may obviate the necessity of respraying.
Many investigations are being carried on to develop low-priced non-
arsenical insecticides which will not be harmful to man or domestic
animals. Improvements along this lme would be most useful for
gypsy moth spraying operations.
Warning.—Lead arsenate is a stomach poison and is toxic to animal
life. Itis unsafe to allow animals to graze underneath trees that have
been recently sprayed. When fish oil is used as an adhesive, the
spray will disfigure paint on buildings or vehicles unless it is removed
with clear water before it has an opportunity to dry. Water may be
provided by a low-pressure pump or from a hydrant. Fruit trees
should not be sprayed with lead arsenate after the fruit is half grown,
as it is difficult to remove the residue.
CLEAN-UP AND THINNING WORK
In many areas satisfactory control work cannot be attempted with-
out the removal, and usually the burning, of infested rubbish and
worthless trees. This should be done in such a way as to improve the
property. Woodland areas may be thinned to advantage by removing
trees that are favored as food by the gypsy moth caterpillars and
encouraging the growth of better species of the less favored classes.
When it is necessary to remove dead or useless wood in trees, the best
practice of pruning and tree care should be employed.
EQUIPMENT
In creosoting work a brush with a round handle, which can be fitted
with a cork stopper into a can containing creosote, is useful for treating
ege clusters within easy reach. Those higher up can be treated w ith
brushes that are attached at an angle to the tip of bamboo poles ranging
from 8 to 18 feet in length. Axes, saws, and bark knives for marking
trees are also necessary.
20 CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
For applying burlap ee ds knives should be supplied for cutting the
burlap and the twine and destroying the caterpillars. For applying
sticky bands, knives or steel brushes should be used to destroy the
caterpillars, and tree scrapers will be required to smooth the rough
bark before the bands are applied.
The most expensive item in gypsy moth work is the spraying ma-
chinery and the equipment necessary to operate it. If orchard trees
or low growth is to be treated, an orchard sprayer equipped with one or
more lines of hose and with nozzles of the vermorel or bordeaux type
will be satisfactory. The object of treatment is, of course, to cover all
the foliage evenly with a thin deposit of spray. The higher the trees
the more difficult it is to apply the material without waste. When
large shade, park, or woodland trees are to be treated, high-powered
spraying apparatus and use of the solid-stream type of treatment will
enable the work to be done rapidly. For best results the machine
should be equipped with hose 1 inch in diameter, and a nozzle pressure
of 300 pounds per square inch should be maintained. The speed of
the pump must be regulated according to the aperture of the nozzle.
Since the quantity of Jiquid passing through increases with the diame-
ter of the tip, the pump pressure has to be stepped up to furnish the
300-pound nozzle pressure necessary to break up the spray. As hose
lines are lengthened or the elevation of the nozzle above the spraying
machine increases, there is a loss of pressure at the nozzle due to the
friction in the hose and the additional height to which the spray
material must be forced. The pump should be of the triplex type,
capable of delivering at least 35 gallons of liquid per minute for a short
spray line. A spray tank of 300 gallons’ capacity is commonly used,
and the tank and suction line should be provided with strainers to
keep out foreign matter, which will either injure the pump or clog the
nozzle.
One-inch hose capable of withstandmg a working pressure of 600
pounds is satisfactory for most park and shade-tree work, where ex-
tremely long lines of hose are not required, or where isolated areas
are to be treated and the equipment has to be moved frequently. On
larger and more extensive areas, or where a water supply is some
distance away, a higher-powered machine and hose that will withstand
a working pressure of 1,000 pounds per square inch are necessary
(fig. 9). To perform a maximum amount of work the sprayer should
be set at the water supply. If the machine is equipped with an
auxiliary pump for drafting water to supply the tank, and the tank
is divided, one section can be filled while the other is being emptied
as the spraying operation proceeds, and continuous spraying will
result. With equipment of this type and on areas where there are
slight elevations, 4,000 to 5,000 feet of hose can be laid to reach
outlying areas.
In the intensive work that is being carried on by the Bureau of
Entomology and Plant Quarantine in some of the outlying areas
longer hose lines are necessary, and on account of higher elevations
the sprayer and the hose are required to pass a performance test of
1,500 pounds’ working pressure. “As much as 12,000 feet of hose has
been used on work of this type. Sprayers are constructed either with
a power take-off or as individual units, so that they can be transferred
to a truck and moved to points where they are needed in the field.
With this type of machinery and the proper diameter of tip on the
a
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 21
nozzle, it is possible to spray thoroughly trees from 60 to 100 feet
high. By using the same type of machine under reduced pressure
and attaching to the nozzle a device known as a spreader, low growth
may be treated rapidly and satisfactorily.
Tests have been made during several seasons with airships, both
heavier-than-air and dirigible types, to determine whether infested
woodland areas could be dusted satisfactorily and economically.
This method has not proved entirely satisfactory up to the present
time. _ During the past year spraying with an autogiro has been tried,
and the results have been more promising. This method has not yet
been perfected sufficiently, however, to warrant its general adoption
for woodland spraying, although for applying dust insecticides on
certain low-growing crops it has given excellent results in some sections
of the country.
METHODS TO BE APPLIED IN ORCHARDS
Of the fruit trees, apple trees are the most likely to be infested
with this insect, and some injury to peach trees has been noted.
FIGURE 9.—High-power truck sprayer.
Apple orchards that are sprayed with lead arsenate for the control of
other insects are protected from the gypsy moth. If systematic care
or spraying of the orchard is not the practice, a program consisting of
the removal of deadwood and defective trees, treatment of egg clus-
ters, and spraying with lead arsenate and fish oil shortly after the
blossoms fall should be put into operation. Orchards that are in
close proximity to infested woodlands are sometimes severely damaged
as a result of dispersion of small caterpillars by the wind or migration
of the larger ones. ‘This can be prevented for the most part by proper
care of the surrounding woodland.
PROTECTION OF SHADE, ORNAMENTAL, AND ROADSIDE TREES
Protection of shade, ornamental, and roadside trees is vital to the
communities and rural districts in which they grow, as they increase
property values. In most thickly settled communities, when street
planting has been done in recent years, maple, elm, and other varie-
ties that are not favored by the gypsy "moth have been planted, but
22 CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
in many areas poplar, linden, willow, and, to a less extent, some of
the oaks have been used. In the rural sections there has been rela-
tively little roadside planting, and most of the shade trees are seedlings
or have developed from sprouts from trees that have previously been
cut. On private grounds there is a wide range of species, both native
and exotic, and on such properties there are frequently many trees
that are suspectible to gypsy moth attack.
To obtain information as to the species that are growing on trunk-
line roads, in the summer of 1936 a hurried survey was made on one
of the principal State roads from the New York State line through
central Massachusetts, swinging southeast, and extending diagonally
through Barnstable County to Orleans on Cape Cod. The route
covered 260 miles of road, 48 miles of which was classified as city
and 212 as rural. The tree growth for 50 feet on each side of the
road was noted, because trees growing within these strips will even-
tually furnish shade for the highway. As a result of this survey 38.5
percent of the trees were rated as favored species, 27 percent were
conifers and beech, which are highly favored during certain stages of
the insect’s development, 26.5 percent were far less favored but occa-
sionally defoliated, and 8 percent were in the unfavored group.
About 51 miles of this road was open country with no trees, and there
were additional areas where trees had been cut and were being replaced
by sprout growth. These sprout, or brush, areas were about 50 per-
cent favored food. The species growing in the wooded areas adjoin-
ing these strips along the highway, and in the forest areas that were
more remote, varied greatly in different localities, but it is estimated
that more than half the tree growth was of favored species.
A survey of this type does not show what conditions exist in sec-
tions north or south of the road that was selected or on rural or unim-
proved roads. A larger percentage of favored food plants might be
expected southward toward Long Island Sound, and of less favored
ones in southern Vermont, New Hampshire, and Maine. ‘The
information obtained, however, indicates the necessity of protecting
roadside trees from the oypsy moth. Officials in charge of tree pro-
tection could well afford to have maps indicating the growth along the
streets under their control as a basis for planning for protection or
replacement of the most desirable species. An endeavor should be
made to remove as much of the favored growth as possible and to
encourage the growth of nonfavored trees. When it is impractical to
do this, treatment should be applied for the protection of the favored
species. Where solid woodland adjoining the road is heavily infested
with the gypsy moth, roadside trees will be denuded by migrating
caterpillars. In such cases protective work should be done to prevent
defoliation, and the methods that can be most economically employed
should be put into practice in an area adjoining the trees along the
roadway. The size of this area will depend upon the severity of the
infestation.
THE WOODLAND PROBLEM 7
In the barrier zone and the adjoining areas, as well as in isolated
infestations beyond the zone, intensive methods must be applied to
curtail the infestation, not only for the benefit of the locality where it
exists, but to prevent the spread of the pest beyond the known
infested area. This makes necessary the use of a combination of the
methods that can be most cheaply applied.
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 22
In the generally infested area it is impracticable to apply such
intensive methods to large woodlands unless the property is of special
esthetic value or to protect other areas that have been intensively
treated. On account of the low value of most of the forest growth,
some relief can be obtained by the adoption of a thinning program
based on the removal of the most favored food trees in order that the
food of the insect may be reduced. This work, together with the
encouragement of the growth of nonfavored species, will assist in
preventing damage by this insect. It can be done by the owner
himself if he makes proper selection of the trees to be removed.
Obviously the best silvicultural practice should be followed in such
selective thinning (figs. 10 and 11). In pure or nearly pure stands of
favored trees clean cutting and the planting of unfavored species is
the best method of building up a resistant stand even though the cost
is considerable, but there are many areas scattered through the
infested territory where clean cutting is not necessary to improve
the stand.
The same principles of thinning, aimed at the creation of more
resistant growth, can be applied by owners even if their property is
not infested, as this will reduce the opportunity for establishment of
this pest. In young plantations of white pine or other conifers favored
species should be removed, and if there are adjoining areas of favored
erowth as many of such species as possible should be removed to
prevent the insect from migrating into the plantations.
RECENT CONTROL WORK IN NEW ENGLAND AND NEW YORK
WOODLANDS
In both the barrier zone and the outlying infested areas intensive
work is being done, most of it in woodland, to exterminate the insect
and to prevent westward spread. In the zone itself such treatment has
eliminated the insect in many localities in Vermont, Massachusetts,
and New York. Isolated colonies are now (1937) being treated in
southwestern Massachusetts and northwestern Connecticut, and in a
few towns in the southern part of New York State. On Long Island
and in the Borough of the Bronx in New York City the infestation
has been greatly reduced. In 1936 a colony was found in Shawangunk,
west of the Hudson River, and intensive treatment is being applied
in this locality.
Between the barrier zone and the Connecticut River isolated colonies
have been found, especially in the territory nearest the river in
Vermont and over a wider area in Massachusetts and Connecticut.
Work similar to that in the barrier zone is being carried on here, the
number of infestations is being reduced, and infestations have been
exterminated.
RECORD OF CLEAN-UP OF OUTLYING COLONIES
A few colonies of the gypsy moth have been discovered at points
quite distant from the generally infested New England region,
notably at Geneva, N. Y., in 1912; at Cleveland, Ohio, in 1914; at
North Castle, Westchester County, N. Y., in 1914; at Rutherford,
N.J., in 1914: and at Greenport, near the eastern end of Long Island,
in 1921. In practically all these cases the Federal Government was
assisted by the States involved in ferreting out the limits of the
AGRICULTURE
DEPARTMENT OF
=
Ne)
CIRCULAR 464, U.
24
FIGURE 10.—Mixed stand of hardwoods and conifers before thinning.
Here white
ed from danger.
as been rele
—Same woodland shown in peure 10 after favored food trees had been removed.
pine as
FIGURE 11
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 25
colonies and applying intensive clean-up measures, and in every case
the colonies have been exterminated.
Since 1921 several other small, scattered infestations have been
found on Long Island (fig. 12), and clean-up work here was undertaken
by the New York Department of
Conservation. Owing to its geo-
graphical location and the general
trend of spread of the insect away
from rather than to this island,
sufficient field work should furnish
ample protection from this pest.
EXTERMINATION PROJECT IN
NEW JERSEY
In July 1920 a State inspector
found the gypsy moth on a large
estate near Somerville, N. J. When
discovered, the infestation centered
in a large plantation of blue spruce
trees, several acres of which were
defoliated. There were dead trees
in the worst-infested portion of the
plantation, with indications that
they had been killed by complete
defoliation (fig. 13).
The trees in this plantation had
been imported from the Nether-
lands about 10 years before, and
the infestation came with the shipment.
FIGURE 12.—Locations, outside of the large New
Jersey and Pennsylvania infestations and the
barrier zone, where the gypsy moth has been
exterminated: 1, Cleveland (Bratenahl), Ohio;
2, Loretto, Pa.; 3, Geneva, N. Y.; 4, Schenec-
tady, N. Y.; 5, North Castle and Garrison,
N. Y.; 6, Brooklyn, Roslyn, Kew Gardens,
Patchogue, Shelter Island, and Greenport on
Long Island, N. Y.; 7, Deal Beach, Wyckoff,
South Orange, Scotch Plains, Paterson, Madi-
son, Glen Rock, Elizabeth, and Rutherford,
N.J.; 8, Henrysburg, Quebec.
This was prior to the en.
actment of the Plant Quarantine Act, and emphasizes the pressing
need for precautionary measures to keep out dangerous pests.
FIGURE 13.—Blue spruce defoliated and killed by the gypsy moth.
26 CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
Scouting during the fall of 1920 and the spring of 1921, financed
by the State of New Jersey and the Federal Government, revealed
infestations of this insect in scattered localities over an area of more
than 400 square miles surrounding Somerville (fig. 14).
FIGURE 14.—Area in New Jersey infested by the gypsy moth in 1921. Dots indicate location of colonies
within the infested area, and dots enclosed in circles indicate isolated colonies.
Previous successes in cleaning up local infestations led to the
adoption of a cooperative plan to clean up this large, newly discovered
infestation. State and Federal funds were appropriated, and the
work was organized under the direction of the field office for gypsy
moth control of the Bureau of Entomology. When the limits of
infestation had been determined, the area was placed under State
quarantine, which required as a condition of movement the certifica-
tion of freedom from infestation of all products likely to carry any
stage of the gypsy moth. Thorough inspection, which permitted
certification, was made in cooperation with the Federal Government and
by Federal inspectors. The area under regulation has been gradually
reduced as a result of the clean-up work, and in 1932 Federal opera-
tions were stopped and all inspection requirements were withdrawn.
As soon as active work was under way in New Jersey, it was learned
that trees had been shipped from the estate on which the insect was
first discovered, and that the danger of its establishment in many
Q)
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL D7
localities was very great. Fortunately, a record of all these ship-
ments was available. It was found that 261 shipments had been sent
to the District of Columbia and the following States: Connecticut,
Delaware, Florida, Illinois, Indiana, Kentucky, Maryland, Minnesota,
Missouri, New York, North Carolina, Ohio, Pennsylvania, Virginia,
and Wisconsin. ‘These shipments were traced and the planted stock
was inspected by State or Federal officials. In addition, 318 ship-
ments that had been distributed in New Jersey were followed up
the same way.
As a result of this work small infestations were found at Loretto,
Pa.; Garrison, Roslyn, and Kew Gardens, N. Y.; and Deal Beach,
Wyckoff, South Orange, Scotch Plains, Paterson, Madison, Glen
Rock, and Elizabeth, N. J. These small infestations were cleaned up
the following year, and repeated scouting has failed to indicate the
presence of the pest.
In the meantime the center of the infested area was receiving in-
tensive treatment, including spraying, and an enormous number of
ego clusters were destroyed. It is significant that no trees in New
Jersey have suffered from gypsy moth feeding since that time. During
the next 4 years scouting and clean-up operations were continued
throughout the known infested area, particular attention being paid
to extensive woodlands north of Somerville, known as the Watchung
Ridge. These areas were heavily wooded and were difficult and
expensive to work.
Since 1925 the gypsy moth has been steadily reduced in numbers.
The scouting and clean-up work covered over 2,369 square miles,
although the towns in which colonies were found were in an area of
924 square miles. Federal operations were discontinued in 1932,
as no infestations had been discovered since 1929. Since 1932 the
State force has been making inspections in many localities and has
uncovered a few small infestations along the northern border of the
old infested area. ‘These have been treated by the Federal Govern-
ment in cooperation with the State. Although a large amount of
intensive work has been done, no infestation has been found during
the past 2 years.
Table 1 shows the number of townships in the barrier zone, New
York, and New Jersey where the gypsy moth has been eradicated and
the number of infestations that have been cleaned up. It indicates the
protection that has been afforded to other sections of the United States.
TaBLE 1.—Townships in the barrier zone, New York, and New Jersey, where
gypsy moth infestations have been eradicated, with the number of infestations
cleaned up, fiscal years 1920-19385
Infestations Infestations
Infested Infested =
State A extermi- State extermi-
townships ata d townships mated
In barrier zone: Number Number South and west of barrier
Connecticut_________- 20 92 zone: Number Number
Massachusetts_______- 27 362 New Jersey__.___-___- 38 878
ING Wa VOnKe ee 24 75 ING winViOE kee 17 567
WeLmMonte eee ese 18 78
a Mo tales. Sates re 55 1, 445
MRotaltaee Boe = 89 607
——_ | ———— Grand total_______- 144 2, 052
28 CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
EXTERMINATION PROJECT IN PENNSYLVANIA
Late in July 1932 a serious infestation was discovered near Pitts-
ton, Luzerne County, Pa., through the location of male moths by
a biology student. A survey was made and scattered infestations
were found over a wide area. An eradication program was adopted
under the supervision of the officials of the Federal Bureau of Ento-
NEW YORK
™ wa ci
; eo
FISCAL YEAR
i935 GYPSY MOTH PROJECT
NORTHEASTERN PENNSYLVANIA
———=_ DELIMITS KNOWN AREA OF GYPSY MOTH
INFESTATION= APPROXIMATELY 410 SQUARE MILES
J
=> 1}
WiLKES}BaRRE®
ono ' NEW JERSEY
e INFESTATION
HARRISBURG
© ISOLATED INFESTATION ez,
MARYLAND
Mmm PENNSYLVANIA QUARANTINE — SEPTEMBER I, 1934
APPROXIMATELY 880 SQUARE MILES
FIGURE 15.—Gypsy moth infestation in northeastern Pennsylvania in 1935.
mology in cooperation with the Pennsylvania Department of Agricul-
ture and Department of Forests and Waters, and an office was estab-
lished in Wilkes-Barre. From the fall of 1932 to the spring of 1933
over 1,200 acres of tree growth were thinned and cleared of brush and
worthless and dead trees in the worst infested portion of the area.
During the same period about 2 million egg clusters were destroyed
by creosoting. In the summer of 1933, 3,200 acres of woodland and
thousands of trees in residential sections and open country were
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 29
sprayed. A larger area was thinned and cleaned during the fall and
winter.
The work has been intensified and expanded since that time, and
there has been a marked decrease in the number of egg clusters treated
each year. Some new infested points have been found, and they have
been promptly treated. No defoliation has been noted since the
first summer. The infested areas and some of the surrounding town-
ships have been placed under a State quarantine, and movement of
materials likely to carry the insect is not permitted until they have
been inspected and certified by officials from the Wilkes-Barre office.
The area infested in 1935 is shown in figure 15. The present
infested area aggregates 680 square miles, and additional areas sur-
rounding it totaling 320 square miles are covered by the quarantine
and inspection regulations. This includes Coolbaugh and Foster,
which were added in 1936.
Substantial progress has been made on this project in Pennsylvania,
and excellent cooperation has been received from the State. The
territory is located in the heart of the anthracite district, and much
of the country is wooded and mountainous, and therefore difficult
to work. Part of this area is in the valley of the Susquehanna and
Lackawanna Rivers, and some infestations have been found in the
Pocono Mountain range. This infestation is located the farthest
west of any in the United States, and the importance of reducing the
abundance of the insect and bringing about its final extermination can-
not be overestimated. If the work is not continued aggressively,
the insect might spread rapidly to surrounding territory and to other
States where it is not now known to exist.
THE BROWN-TAIL MOTH
HISTORY OF THE PEST IN THE UNITED STATES
The brown-tail moth (Nygmia phaeorrhoea Don.) was first found in
the United States in Somerville, Mass., in the summer of 1897, and
was undoubtedly introduced several seasons previous to that time on
imported nursery stock. The insect increased enormously, and as the
caterpillars were fond of the foliage of fruit and ornamental trees and
shrubs, they became an unbearable nuisance, particularly in residential
sections. Not only was complete defoliation common early in the
summer, but as the hairs from the caterpillars caused serious poisoning
to human beings the presence of this pest became a veritable scourge
in densely populated areas. The insect extended its range very
rapidly, because the moths of both sexes fly freely. This species
occurs in many parts of Europe and is frequently very injurious.
The State of Massachusetts applied suppressive measures from the
winter of 1897 until February 1900, when it discontinued the work
along with that of the gypsy moth. By 1905 the brown-tail moth was
extremely abundant in eastern Massachusetts. It was also present
in enormous numbers in Rhode Island, southern New Hampshire,
and southwestern Maine. Not only did fruit and shade trees suffer
defoliation, but large areas of oak woodland, particularly sprout
erowth, were completely defoliated.
30 CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
The insect continued to spread until 1915, when most of the area
east of the Connecticut River, with the exception of a portion of
northern New Hampshire and Maine, was heavily infested. Some
infestation also existed in Vermont and west of the Connecticut River
TJodener. pipe: :
FIGURE 16.—Life stages of the brown-tail moth: A, Winter nest; B, male pupa; C, female pupa; D, cocoon
in leaves; H, young caterpillars on leaf; F, full-grown caterpillar; G, female depositing eggs on a leaf, and
egg mass also on leaf; H, egg mass removed from leaf and with some of the eggs exposed; J, male moth;
J, female moth. All about three-fourths natural size.
in Massachusetts and Connecticut. Suppressive work carried on
by the States and the Federal Government kept the residential
sections fairly free from this pest.
The area now infested by the brown-tail moth is shown in figure 1,
and is much less extensive than formerly. Low winter temperatures,
Oi
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 31
particularly in the northern part of the territory, coupled with the
work of natural enemies and disease and the continuous repressive
measures used in the residential sections, have caused a remarkable
decrease in the abundance of this pest. The insect has been found
in Nova Scotia and New Brunswick, but has not been reported from
there in excessive numbers for several years.
This pest can easily be shipped on woody plants, but general spread
in this manner has been prevented by the strict enforcement of
inspection and quarantine regulations.
LIFE HISTORY
The different stages in the development of the brown-tail moth are
shown in figure 16.
THE EGGS
The female moth deposits a small cluster of from 200 to 400 eggs
on the underside of a leaf. They are usually laid in July, and are
covered with brown hairs from the body of the female. Hatching
begins about August 15.
THE LARVAE
The newly hatched larvae, or caterpillars, feed on the epidermis of
the leaf. After molting once or twice they construct a winter web.
This is made by drawing together several terminal leaves and fasten-
ing them with silk which they secrete. The larvae from one or more
ege clusters live and feed in common, and as cold weather approaches
they retire to the web, in which they remain during the winter. In
the spring, as soon as the buds begin to develop, the larvae leave the
web and feed upon the bud scales and small leaflets. As they increase
in size they consume most of the foliage. They become full grown
late in June.
The full-grown larva, which is hairy, is about 14 inches long. The
head is light brown. The body is dark brown to almost black, with
a broken white line on each side and two conspicuous reddish spots
on the dorsum near the posterior end.
THE PUPAE
After the caterpillars have finished feeding, they spin loose silken
cocoons in which to pupate. These cocoons may be constructed sep-
arately, or large numbers may be spun in a single mass. Sometimes
leaves are drawn together as shelters; in other cases the cocoons are
attached to trees or other objects. About 2 weeks is spent in the
pupal stage.
THE ADULTS
Emergence of the moths usually begins the first week in July.
The adult is pure white, except for the tip of the abdomen, which is
covered with brown hairs. The body of the female is much larger
than that of the male. These moths are attracted to strong light,
and as they fly at night they are often seen around electric lights in
cities and towns during the first half of July.
FOOD PLANTS
The caterpillars of the brown-tail moth feed on the leaves of apple,
pear, cherry, oak, and willow, and they are sometimes found in con-
siderable numbers on other common deciduous trees and shrubs.
32 CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
They never attack conifers and are seldom found on hickory, ash, or
other trees.
Oak foliage is one of the favored foods of the brown-tail moth cat-
erpillars in Europe and was severely injured in New England for a
number of years after this insect became established there. It has not
suffered in this way in recent years except in Maine and New Hamp-
shire in 1933, when the insect was unusually abundant, and then some
webs were found on oak trees and the caterpillars caused considerable
defoliation locally.
INJURY CAUSED BY THE BROWN-TAIL MOTH
The principal injury caused by the brown-tail moth is due to the
feeding of the larvae in the spring. ‘The caterpillars are often numer-
FIGURE 17.—Apple trees defoliated by the brown-tail motn. Note the hibernating webs on the twigs.
ous enough to devour the leaves as fast as the trees are able to develop
them. As the webs are made on the terminals, the growth of the
trees is often severely checked. In severe infestations trees may be
completely stripped (fig. 17), but as the larvae grow rapidly during
the first part of June there is usually an opportunity for the trees to
produce new leaves before midsummer. The larvae hatch in August
and frequently skeletonize the leaves, but this does not damage the
trees seriously, as the growing period for the season is nearly over.
The bodies of the caterpillars are provided with poisonous hairs.
A microscopic examination of these hairs shows that the edges are
barbed in such a way as to cause intense irritation when they come in
contact with the human skin. They are also hollow and contain a
substance which acts on the blood corpuscles. Poisoning and irrita-
tion caused by this insect are accompanied by external swelling, and is
known as the brown-tail rash. Persons differ in their susceptibility
to this poison, but many cases are reported each year in the infested
area. Many camps and summer cottages cannot be occupied with
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 30
any comfort during the early summer if the caterpillars are abundant.
If clothing is hung on the line near badly infested trees, the hairs
frequently find lodgment and are brought into the houses, with
consequent poisoning of the inhabitants.
NATIVE ENEMIES
One of the important native enemies of the brown-tail moth is a
fungus disease (Hntomophthora aulicae Reich.) which attacks the
caterpillars. It was first reported in this country by Roland Thaxter
in 1888. Like all diseases of this nature, the benefit derived from it
is regulated largely by weather conditions. This fungus sometimes
works to a slight degree on the small caterpillars in the fall, and is
found occasionally in the winter webs. As a rule, however, the
greatest mortality of caterpillars takes place in the spring, when they
are nearly full grown, and the pupae may, under the most favorable
conditions, be almost completely exterminated.
Native parasites and predacious insects have done little to check
the increase of the brown-tail moth.
INTRODUCED PARASITES AND OTHER ENEMIES
Compsilura concinnata Meig., one of the species introduced as an
enemy of the gypsy moth, attacks the caterpillars of the brown-tail
moth freely, while two others, Apanteles lacteicolor Vier. and Sturmia
midicola Towns., that were introduced from Europe at about the
same time are also important enemies of the insect. Other imported
enemies, Carcelia laxifrons Vill., Meteorus versicolor Wesm., and
Eupteromalus nidulans Foerst., that have become established help to
reduce the numbers of the moth but are not usually of great importance.
EFFECT OF LOW TEMPERATURES
Extremely low temperatures in the winter often prove fatal to a
large proportion of the small caterpillars in the webs. When unpro-
tected by snow or other covering, they are usually killed by tempera-
tures below —25° F.
METHODS OF CONTROL
The brown-tail moth can be controlled by cutting off the winter
webs and burning them before the caterpillars begin to emerge in
April. These webs should be destroyed by fire, for if they are simply
cut from the trees and left on the ground, the caterpillars will emerge
and no benefit will result from the work that has been done.
In orchards it is sometimes inadvisable to cut the winter webs, for
where an infestation is heavy the cutting is likely to leave poorly
shaped trees. Spraying in the spring is not a satisfactory remedy
unless the infestation is very light, because large numbers of cater-
pillars do not allow the tree to put out sufficient foliage to hold the
spray material.
An effective method in orchards is to spray the trees before the
middle of August, using 3 pounds of powdered lead arsenate to 100
gallons of water. Before doing so the orchardist should determine
to what extent the trees are infested with egg masses of the brown-
tail moth. In spraying fruit trees, particularly early fall varieties,
34 CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
caution should be used to avoid excessive spray residues. The
foliage should be treated, particularly the terminal shoots, and care
should be taken not to cover the fruit. Late fall or winter varieties
of fruit may be sprayed with lead arsenate in August, and although
an occasional spot may be found on the fruit at the time of picking,
no injury will result from it. Where only a few choice fruit trees
are sprayed, it is practicable to wipe the fruit before packing it for sale.
The damage caused by the brown-tail moth is ordinarily not so
severe as that due to the gypsy moth, because the brown-tail moth
does not have so wide a range of food plants and, since most of the
feeding is done early in the season, the trees have an opportunity
to recover before midsummer. In the territory where both insects
exist the caterpillars of the gypsy moth supplement the feeding done
by those of the brown-tail moth, and the injury is therefore greatly
increased.
Thorough destruction of the webs in residential sections and in
orchards has materially reduced the infestation in such places. Elim-
ination of worthless apple and wild cherry trees would help greatly
in reducing the pest.
RECENT CONTROL EFFORTS
In the winter of 1933-34 an extensive Civil Works Administration
brown-tail-moth project was carried on, under the direction of the
Bureau of Entomology in cooperation with the New England States,
in which almost 24 million webs were cut and burned. Although
the insect was much less abundant the following summer, during the
winter of 1934-35 almost 2 million webs were cut and destroyed by
State officials using local or State funds. The following winter a
Works Progress Administration project was conducted by the Bureau
in cooperation with the States, and more than 4% million webs were
destroyed. The work was continued during the winter of 1936-37,
and up to the end of March more than 2% million webs had been
cut and destroyed.
The destruction of such large numbers of winter webs has resulted
in a decided decrease in infestation over much of the infested area.
Prior to the C. W. A. work heavy defoliation was common in many
parts of this area. During the past summer little defoliation was
found. ‘Towns have been found in all the infested States where no
infestation could be located, and it should be possible to reduce the
affected territory materially if the work is continued.
ORGANIZATION AND STATUS OF WORK AGAINST THE
GYPSY MOTH AND THE BROWN-TAIL MOTH
Each State infested with the gypsy moth and the brown-tail moth
is carrying on control work, and many of the towns and cities are
similarly engaged. The Dominion of Canada and several of the
Provinces have also taken up control and eradication work.
MAINE
In Maine the work is in charge of the commissioner of agriculture,
who has authority to appoint assistants to supervise the operations.
In the southwestern part of the State the gypsy moth infestation is
>| =
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 35
general and, in places, severe; the northern part of the insect’s range
is only lightly infested. The severity of infestation increased in 1932
and 1933, and many heavily infested sections have been found since
that time. Several small infestations were found in the eastern
part of Washington County in 1936. The brown-tail moth was
very abundant in the southwestern part of Maine from 1931 to 1933,
but the wholesale cutting of the webs has greatly reduced the in-
festation. Over 12,000 square miles in the State are infested with
the gypsy moth, and about 7,000 with the brown-tail moth. The
latter has been spreading to new territory since 1931.
NEW HAMPSHIRE
The moth work in New Hampshire is in charge of the State ento-
mologist. Over 8,000 square miles are infested with the gypsy moth
and about 5,000 square miles with the brown-tail moth. Most of
the territory from Lake Winnipesaukee south to the Massachusetts
line has suffered severe and repeated defoliation from the gypsy
moth. The territory directly north and northeast of the lake has
also had considerable defoliation. The same areas were heavily
infested with the brown-tail moth from 1931 to 1933. Since that
time the infestation has been greatly reduced by control work, and
also, in some sections, by winter mortality of the larvae.
VERMONT
In Vermont the moth work is in charge of the commissioner of
agriculture, who appoints an entomologist to carry on the field work.
After intensive scouting for the gypsy moth in the winter of 1933-34,
the area under quarantine was reduced from about 6,000 to 4,500
square miles. The heaviest infestations are located along the Con-
necticut River. Only a few brown-tail moth infestations have been
found in Vermont in recent years. A survey along the eastern border
of the State in 1933 and 1934 indicated a number of scattered in-
festations, and this area was placed under quarantine. As a result
of work done since that time no infestation by this insect has been
found during the last 2 years.
MASSACHUSETTS
The commissioner of conservation has charge of the moth work in
Massachusetts. Each infested town is required by law to select a
local superintendent, whose appointment must be approved by the
commissioner. Owners are required by law to keep their property
free from these pests, but cannot be compelled to expend for this
puruose more than $5 per year on each $1,000 assessed valuation.
owns and cities must provide for proper treatment of the street
trees and those in parks and on public grounds. After the amounts
fixed by law are expended, financial aid may be supplied by the
State. The gypsy moth at present (1937) occurs in every town in
the State east of Berkshire County. It has increased in abundance
over much of the infested area during the last 3 years, especially in
the towns directly east of the Connecticut River. The area infested
by the brown-tail moth is a little over 4,500 square miles.
36 CIRCULAR 464, U. S. DEPARTMENT OF AGRICULTURE
RHODE ISLAND
In Rhode Island the commissioner of agriculture has charge of the
moth work, which is done under the supervision of the State ento-
mologist. The gypsy moth occurs in all towns in the State. Since
1931 the infestation has increased rapidly, and in 1934 much defolia-
tion was noted. The conditions approximate those which the State
of Massachusetts has encountered for many years. No brown-tail
moth infestation had been found for a number of years prior to 1936,
when a few webs were found in two towns in the eastern part of the
State.
CONNECTICUT
In Connecticut the work is in charge of the State entomologist.
The brown-tail moth has not been found in this State for several
years. The area infested by the gypsy moth is now about 3,000
square miles. During the past 3 years the infestation has increased
noticeably in some localities in the eastern part of the State.
NEW YORK
In New York State the work is supervised by the Department of
Conservation, which is cooperating with the Federal Bureau of Ento-
mology and Plant Quarantine in the New York section of the barrier
zone. <A few scattered infestations in eastern New York and on Long
Island, including New York City, and a newly discovered infestation
at Shawangunk, west of the barrier zone, are being treated by the
State. During the past 2 years a special survey of the entire State
has been made, but no additional infestations have been found.
NEW JERSEY
In New Jersey the State work is under the control of the State
Department of Agriculture. The funds appropriated have been
used in conjunction with Federal funds, and the work is supervised
by the Bureau of Entomology and Plant Quarantine. No infesta-
tion has been found for 2 years.
PENNSYLVANIA
In Pennsylvania the work is carried on under the direct supervision
of the Bureau of Entomology and Plant Quarantine of the United
States Department of Agriculture, with the cooperation of the Penn-
sylvania Department of Agriculture and Department of Forests and
Waters. Progress has been made in the eradication work conducted
in this State.
DOMINION OF CANADA
Scouting for the gypsy moth and the brown-tail moth in Canada is
conducted by the Division of Foreign Pests Suppression of the office
of the Government entomologist. Cooperation with the provincial
governments of New Brunswick, Nova Scotia, and Quebec has been
maintained. The gypsy moth colony found at Henrysburg, Quebec,
has been exterminated through the efforts of the Dominion and pro-
vincial officials. Late in 1936 a few gypsy moth egg clusters were
found in and around St. Stephen, New Brunswick, and extensive
scouting and clean-up work has been done.
GYPSY AND BROWN-TAIL MOTHS AND THEIR CONTROL 37
UNITED STATES DEPARTMENT OF AGRICULTURE
The gypsy moth project has been conducted by the Bureau of
Entomology for many years. On July 1, 1928, the quarantine and
control work was transferred to the Plant Quarantine and Control
Administration, which later became the Bureau of Plant Quarantine,
and the research work was assigned to the Division of Forest Insects
of the Bureau of Entomology. On January 1, 1934, the quarantine
work was transferred to another section of the Bureau, and on July 1,
1934, the two bureaus became the Bureau of Entomology and Plant
Quarantine.
For a number of years it was believed to be impossible to restrict
the spread of the brown-tail moth on account of the heavy migration
of the adults. Owing, however, to the effectiveness of parasites
introduced by the Bureau, to winter conditions unfavorable to the
insect, and in some sections to the effectiveness of a fungus disease
that attacks the caterpillars, in addition to a large amount of hand
suppression work, not only was spread prevented but marked reduc-
tion in the infested area recorded.
A large amount of experimental work has been done to devise
better methods of controlling these insects. Natural enemies have
been introduced from Europe, northern Africa, and Japan and colo-
nized throughout most of the infested area. Specialists have spent
considerable time studying the insects in their native homes and col-
lecting parasites for shipment to this country.
The entire area known to be infested by either of these insects is
under quarantine, and shipments of nursery stock, lumber, cordwood,
and other forest products, including Christmas trees and greenery
and stone and quarry products, are not permitted to leave the terri-
tory unless they are inspected and accompanied by a certificate
stating that they are free from infestation.
The results of the work in the barrier zone in preventing spread
and the cleaning up of isolated infestations have justified the efforts
expended and have protected the United States at large from infesta-
tions and resultant damage from these pests.
COOPERATIVE WORK
Since the gypsy moth and brown-tail moth work was begun by the
Bureau of Entomology, more or less work has been done in coopera-
tion with the States concerned. The general plan of field work in
New England is for the States to manage the clean-up east of the
barrier zone while the Federal forces work in the zone and cooperate
in making the entire work effective.
In New York the work in the barrier zone is handled in cooperation
with the State authorities.
In New Jersey and Pennsylvania close cooperation has been main-
tained with the State departments.
During the past 3 years the work has been extended and intensified
through cooperation with the N. R. A., W. P. A., and C. C. C., and
recently cooperation has been established with the Northeastern
Forest Experiment Station of the Forest Service for the purpose of
utilizing the latest silvicultural methods in connection with the control
work in forests.
ORGANIZATION OF THE UNITED STATES DEPARTMENT OF AGRICULTURE
WHEN THIS PUBLICATION WAS LAST PRINTED
Secretary of Agniculiine=== sae. | Henry A. WALLACE. {
Under Secretary = ae ee Pee M. L. Wiuson.
Assisiant SeChela ites 455 ee oe eg Harry L. Brown.
Director of Hatension, Work a= 2. ae ae C. W. WARBURTON.
Director ofpliinance: 22 a ae W. A. Jump.
Director, of Informations =.= see es M. 8S. EISENHOWER.
Darectorsofeeersonnela =o == Cee W. W. STOCKBERGER.
Direction OfeiteSear Chia see eee © eee James T. JARDINE.
SolieuOp eo eee: - eee Mastin G. WHITE.
Agriculiural Adjustment Administration ____- H. R. Totuny, Administrator.
Bureau of Agricultural Economics________-_- A. G. Buack, Chief.
Bureau of Agricultural Engineering________- S. H. McCrory, Chief.
BUrean Of; ANUMGLLngUstin) =e eee JoHn R. MouueEr, Chief.
Bureau of Biological Survey_——-.__--_=--__- Ira N. GABRIELSON, Chief.
Bureau of Chemistry and Soils____________- Henry G. Kniaut, Chief.
Commodity Exchange Administration________ J. W. T. Duveu, Chief.
Bureau of, Dainyslndusicy 2 oe O. E. ReeEp, Chief.
Bureau of Entomology and Plant Quarantine. Liz A. Strrone, Chief.
Office of Experiment Stations______-_-__---- JAMES T. JARDINE, Chief.
Farmisecumty Administration. =— 2 =e =e W. W. ALEXANDER, Administrator.
Food and Drug Administration_____--_---_-~- WatrerR G. CAMPBELL, Chief.
THiOnestySerutce 2 Nas Nn eee ee! 82 ee FERDINAND A. Siucox, Chief.
Bureau Of MAomeseConomicss2 = se ee LovutsE STANLEY, Chief.
YA OG ah 0 se ore eae ese at er ee a So 28s CLARIBEL R. Barnett, Librarian.
BUneaw Of lant ANdUSiiy = 2 =a eee EK. C. AucHTER, Chief.
Bureau, eublic oad seen! ee = eee Tuomas H. MacDona.tp, Chief.
Soil Conservation Service___-_ ~~ exit: eee H. H. Bennett, Chief.
Weather Buncat= 525 es sss 1 ee Wiuuis R. Greae, Chief.
This circular is a contribution from
Bureau of Entomology and Plant Quarantine. LeE A. Srrone, Chief.
Division of Gypsy Moth and Brown-Tail A. F. Buresss, Principal Entomol-
Moth Control. ogist, in charge.
Division of Forest Insect Investigations__ F. C. CRAIGHEAD, Principal En-
tomologist, in charge. )
38 qi
U.S. GOVERNMENT PRINTING OFFICE: 1938
For sale by the Superintendent of Documents, Washington, D.C. - - - - Price 10 cents
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