Gypsy moth handbook : the homeowner and the gypsy moth : guidelines for control

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Title:
Gypsy moth handbook : the homeowner and the gypsy moth : guidelines for control
Series Title:
Home and garden bulletin ;
Physical Description:
34 p. : col. ill. ; 24 cm.
Language:
English
Creator:
McManus, Michael L
Houston, David R., 001212719
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Dept. of Agriculture :
For sale by the Supt. of Docs., U.S. Govt. Print. Off.
Place of Publication:
Washington
Publication Date:

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Subjects / Keywords:
Gypsy moth -- Control -- United States   ( lcsh )
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bibliography   ( marcgt )
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references (p. 34).
General Note:
Combined forest pest research and development program.
General Note:
"Issued Aug. 1979"--p. 34.
Statement of Responsibility:
by Michael L. McManus, David R. Houston, and William E. Wallner.

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University of Florida
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All applicable rights reserved by the source institution and holding location.
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aleph - 001212719
notis - AFW3000
oclc - 05860058
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AA00009157:00001


This item is only available as the following downloads:


Full Text
,: United States
f l Department of
\~b Agriculture
Combined Forest Pest
Research and
Development Program


Home and Garden Bulletin
No. 227


Gypsy Moth
Handbook


The
Homeowner
and
the Gypsy
Moth:
Guidelines for
Control


A.'


#I


S41 A 1








































Digitized by the Internet Archive
in 2011 with funding from
University of Florida, George A. Smathers Libraries with support from LYRASIS and the Sloan Foundation


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Contents


In 1974 the U.S. Department of
Agriculture initiated the
Combined Forest Pest Research
and Development Program, an
interagency effort that
concentrated on the Douglas-fir
tussock moth in the West, on
the southern pine beetle in the
South, and on the gypsy moth
in the Northeast. The work
reported in this publication was
funded in whole or in part by
the program. This manual is
one in a series on the gypsy
moth.


Introduction
Life History and Life Stages
Egg masses
Egg hatch and spread of
larvae
Early-stage larvae
Late-stage larvae
Pupae
Adults
Detecting the Gypsy Moth
Egg masses
Larvae and pupae
Hosts of the Gypsy Moth
Effects of Defoliation on Trees
Tree condition
Number and severity of
previous defoliations
Mortality-causing organisms
Managing the Gypsy Moth
The natural enemy complex
Guidelines for tree survival
References




The Homeowner and the Introduction
Gypsy Moth:
Guidelines for Control
by
Michael L. McManus, David R.
Houston, and William E. Wallner I


The gypsy moth is the most
important defoliating insect of
hardwood trees in the Eastern
United States (fig. 1). Since the
turn of the century, millions of
dollars have been spent in efforts
to control or eliminate gypsy
moth populations and to retard
natural and artificial spread. In
the early decades of this century,
outbreaks occurred only in New
England; today defoliation by the
gypsy moth is far more severe
and widespread (fig. 2).

The gypsy moth has always been
a "people problem." Defoliation
often occurs in populated areas,
especially where homes and
developments are located in
previously forested land (fig. 3).
Under these conditions, the gypsy
moth defoliates not only
woodland trees but also valuable
park and ornamental trees.
Because the insect is firmly
established in the densely
populated regions of the Eastern
United States, it is very likely
that you, the homeowner in this
area, and the gypsy moth will
meet.

In urban situations, gypsy moth
larvae (caterpillars) are a major
nuisance as they defoliate shade
and ornamental trees, crawl over
everything-homes, outdoor



'Respectively, program coordinator,
principal plant pathologist, and research
entomologist, U. S. Department of
Agriculture, Northeastern Forest
Experiment Station, Hamden, Conn.






































































Figure 1.-Late-stage gypsy
moth larva.


Figure 3.-Partial defoliation
around suburban homesite.


Figure 2.-Extensive defoliation
on ridgetops caused by gypsy moth.













furniture, lawns-and leave debris
from their feeding (figs. 4 and 5).
Should it occur, the death of
defoliated trees and the often
substantial cost of their removal
and replacement can add to the
homeowner's distress.

Although the gypsy moth is well
I .established as a component of
I M the predominantly oak hardwood
forest community of North
America, there are ways to
minimize its adverse effects on
trees and to reduce its impact on
people. Use this guide to
acquaint yourself with the habits
of the gypsy moth, maintain
active surveillance for its presence
or increase, and use those
procedures that are most
appropriate for your situation. If
you are uncertain about which
actions to take, consult with a
representative of the county
cooperative extension office, the
State agriculture service, or the
U. S. Department of Agriculture,
or contact specialists at a nearby
university or agricultural
experiment station.





Figure 4.-Hungry larvae
crawling over home.
Figure 5.-Nuisance of larvae
and frass on picnic table.





Life History and Life Stages


Egg Masses


The female gypsy moth deposits
her eggs in a well-formed egg
mass (fig. 6) in June or July and
dies shortly thereafter. An egg
mass may contain from 75 to
1,000 eggs. It is buff colored
when first laid but may bleach
out over the winter months when
exposed to direct sunlight and
weathering.

Egg-mass size is an indicator of
the status of a gypsy moth
infestation. Declining outbreaks


are characterized by the presence
of many small masses
(approximately 0.5 in long) that
contain as few as 75 to 100 eggs.
In static or growing populations,
the egg masses are fewer in
number but larger (1.5 in long)
and contain from 700 to 1,000
eggs.
Figure 6.-Female moth
depositing egg mass.







Egg Hatch and Spread of Larvae


Gypsy moth larvae usually begin
emerging from individual egg
masses in late April or early
May. Initial hatch is determined
primarily by temperature and
usually coincides with budbreak
of most hardwood trees. The eggs
in an individual egg mass will
hatch completely over a period of
3 to 5 days, but in an infested
area eggs may hatch over a
period of 2 to 3 weeks,
depending on the location of egg
masses and their exposure to
sunlight. Newly hatched larvae
are buff colored but turn black


within 4 hours after emergence
(fig. 7). They remain on or
around the egg mass for several
days if temperatures are below
400 F or if it is raining.

When conditions are favorable,
larvae leave the egg mass and
climb trees in response to
overhead light. They produce silk
from glands located in their head
Figure 7.-Egg mass hatching in
early spring; buff-colored larvae
have emerged most recently.






























kv -

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\-


and lay down a trail of silk
continually as they move (fig. 8).
When larvae reach the outer
branches or tops of trees, they
drop on silken threads (fig. 9)
that are easily fractured by slight
gusts of wind. Both the silk
strand and long lateral hairs
(fig. 10) add buoyancy to the
windborne insects. In woodland
situations, larvae may go through
several windblown dispersals
before settling down to feed.
Although some larvae may be
carried for long distances by
wind, most spread results in


massive redistribution of the
population within relatively local
areas.

Figure 8.-Newly hatched larvae
trailing silk prior to dispersing.
Figure 9.-Larva suspended on
a silken thread.
Figure 10.-First-stage larva
with long lateral hairs.







Early-Stage Larvae


After dispersing, larvae begin
feeding when they encounter
acceptable food plants, which
include many species. In some
years, larval emergence and
dispersal may occur prior to leaf
expansion of favored tree species
such as the oaks; usually
however, larvae can sustain
themselves by feeding on tree
buds and on many understory
plants or shrubs until trees bear
leaves.

First-stage larvae, which usually
have two or three feeding periods
during the day, chew small holes
within the perimeter of the leaf
(fig. 11). When not feeding, they
rest on a mat of silk they have


made on the underside of a leaf.
Male larvae molt (shed the outer
skin) through five stages, females
through six. Each larval stage
lasts 4 to 10 days, the time
dependent mainly on temperature
during each developmental stage.

Second- and third-stage larvae
(fig. 12) feed at the leaf margins
and characteristically stay in the
tree tops, migrating to the
undersides of branches and twigs
when not feeding.
Figure 11.-Typical feeding
damage caused by young larvae.
Figure 12.-A third-stage larva.








Late-Stage Larvae


After molt to the fourth stage
(fig. 13), larval behavior changes
dramatically. Larvae feed during
the night, then descend the trees
at dawn in search of protective
locations where they rest for the
remainder of the day. At dusk
they climb the trees again to
feed. The movement up and
down the tree is apparently
triggered by light intensity. It is
during this stage of development
that defoliation can be severe
enough to be noticed.

Larvae prefer to rest under bark
flaps or other structures on trees
(fig. 14). If no hiding place is
available on trees, the insects will
descend to the ground and rest


Figure 13.-Newly emerged
fourth-stage larva.
Figure 14.-A bark flap
provides protection for gypsy
moth larvae and pupae.
































4 ,.


beneath leaf litter (fig.15), dead
stumps, or other nearby objects.
Here they are often vulnerable to
attack by small mammal
predators such as mice, shrews,
and insects such as ground
beetles. At very high densities,
the larvae follow a different
pattern of behavior-they remain
on the foliage and feed


continuously day and night
(fig. 16).
Figure 15.-Late-stage larvae
resting in leaf litter at base of
tree.
Figure 16.-Foliage being
stripped by many late-stage
larvae.








Pupae


Larvae usually complete their
development in late June or early
July, attach themselves to a
surface with strands of silk, and
then transform into pupae (fig.
17). Usually this is in the same
locations where they rested as
late-stage larvae. Pupation lasts
about 2 weeks. Males usually
pupate before females because
they pass through one less larval
stage. The mahogany-colored
pupae are immobile and
defenseless and are vulnerable to
many different predators and
parasites. Female pupae are
usually larger than male pupae
(fig. 18); however, in dense
populations where available
foliage is limited, female and
male pupae may be the same
size.


Figure 17.-Newly formed
pupae attached to bark with
silken threads.
Figure 18.-Male (left) and
female pupae.








Adults


Male moths usually emerge
before females (fig. 19). Males
are strong fliers and are usually
most active within the forest
canopy during daylight hours.
They fly in zigzag patterns and
can be seen searching up and
down tree trunks for female
moths.


The female moth has well-
developed wings but cannot fly.
She compensates for this by
releasing a strong sex attractant
from her abdomen that lures
male moths to her location. Soon
after mating occurs, the female
deposits her eggs in a single
mass, usually in the same
location where she pupated.

19A















Figure 19.-Adult moths: A,
Male; B, female.





Detecting the Gypsy Moth


Egg Masses


The presence of the gypsy moth
often goes unnoticed until trees
are partially defoliated. This
section describes how and where
to find the insect's life stages
before they become so numerous
as to cause damage.


Gypsy moth egg masses are the
life stage most often observed,
mainly because they are present
in the field from July to May
and persist even after the larvae
emerge. New egg masses are firm
to the touch; hatched egg masses
are soft and spongy. Although
egg masses may be found
anywhere from in the leaf litter
on the forest floor to the tops of
trees, most are laid on the trees,
especially in protected refuges
such as bark flaps, crevices, and
holes (fig. 20).


Figure 20.-Good places to
check for egg masses: A, Bark
flaps; B, holes in trees.














In suburban areas, egg masses
are frequently found in
woodpiles, rock walls, or other I.t '1 21B
protected locations around or on
homes. Homeowners should also
check lawn furniture, behind -
shutters, underneath tree houses,
and beneath lower rows of
shingles on a house or garage
(fig. 21).

Figure 21.-Suburban areas
where egg masses can be found:
A, Woodpile at the base of this
tree is a likely place to find egg 2.
masses; B, stone walls may
contain many egg masses and
other life stages; C, old pupal .; ."
skins and a hatching egg mass ,I,,,
at base of same stone wall; D, Z
tree houses also make good
homes for gypsy moths.


2 1D







Larvae and Pupae


441J "i I I (I I-11
When the feeding and resting
behavior of late-stage larvae
changes, they search out places
to rest during the day either on
the trees or on the ground.
Ultimately the larvae pupate in
these same places (fig. 22).
Burlap bands or skirts placed
about tree trunks of preferred
species such as oaks can aid the
homeowner to detect the presence
of gypsy moth larvae before
noticeable defoliation occurs.
Larvae climbing down the trees
early in the morning will locate
and crawl beneath the burlap
where they can be observed or
periodically removed and
destroyed.

Burlap bands or skirts should be
less than one-half the diameter of
the tree wide and should be


attached at about 5 ft above the
ground. The burlap should be
folded in half and either stapled
to the tree from within the fold
or draped over a piece of string
or rope which is then tied
around the tree (fig. 23). It is
important that the folded burlap
is loosely attached to the tree so
that the larvae are able to crawl
beneath it from either the bottom
or the sides.

Figure 22.-Larvae and pupae
readily use bark flaps for resting
sites.
Figure 23.-Burlap band
(attached with twine) containing
gypsy moth pupae.


1~


, 23
9




Hosts of the Gypsy Moth


Various reports indicate that
gypsy moth larvae can feed on at
least 500 species of plants that
include trees, shrubs, and vines.
This host list will continue to
grow as the gypsy moth spreads
to the South and West. For
example, it has recently been
shown that gypsy moth larvae
can successfully feed and develop
on many cultivated trees, shrubs,
and vines important to agriculture
in California.

In the East, the gypsy moth's
favorite trees include apple,
speckled alder, basswood, gray
and river birch, hawthorne, oak,
poplar, and willow. Less desired
but still attacked are black,
yellow, and paper birch, cherry,
cottonwood, elm, blackgum,
hickory, hornbeam, larch, maple
and sassafras. Older gypsy moth
larvae devour the foliage of
several species that younger
larvae normally avoid, such as


hemlock, southern white cedar,
and the pines and spruces native
to the East.

The gypsy moth avoids ash,
balsam fir, butternut, black
walnut, catalpa, red cedar,
flowering dogwood, American
holly, locust, sycamore, and
yellow or tulip poplar, and
shrubs such as mountain laurel
(fig. 24), rhododendron, and
arborvitae.

This list is provided only as a
guideline for possible
consideration in choosing
landscape plantings. The
susceptibility of less preferred
species to defoliation also
depends upon the species
composition of forests in the
surrounding area and the severity
of nearby infestations.
Figure 24.-Laurel was ignored
by larvae, although surrounding
trees were defoliated.





Effects of Defoliation on
Trees






25


L-N


One must see an episode of
severe defoliation by the gypsy
moth to appreciate fully the
dramatic impact this insect can
have. Most noticeable, of course,
is the great change in appearance
of yards and gardens, when
autumn appears to have arrived
months ahead of time. Sometimes
these visual effects are temporary,
lasting but a few weeks until a
new set of leaves is produced.

Sometimes, however, because trees
may be seriously weakened by
defoliation, the effects are long
lasting. Tree tops may become
thin and off color, and buds and


branches may die (fig. 25); some
trees may die altogether.

Whether or not a tree succumbs
to defoliation by the gypsy moth
depends on three main factors:
Tree condition, the number and
severity of prior defoliations, and
the presence of organisms that
attack and kill stressed trees.
Figure 25.-Dieback of upper
branches on a stressed tree.







Number and Severity of Previous
Defoliations


Trees weakened by construction
(by being wounded, by water
being altered, or by sudden
exposure to drying winds or
bright, hot sun) or by other
stress agents such as too little or
too much water, frosts, leaf
diseases, or herbicides are likely
to suffer more drastically from
gypsy moth defoliation than
healthy, nonstressed trees. But
even healthy trees can suffer
from defoliation if enough of
their leaves are removed in
successive years.


How severely can trees be
defoliated and not suffer? How
often can this occur before trees
are adversely affected? Although
there are no simple answers to
these questions, a general rule is
that a tree is seriously affected
by defoliation when enough
leaves are removed to cause it to
produce a second crop of leaves
in the same growing season. This
process is called refoliation.

Because leaves produce the food
required by the tree for life and
growth, any reduction in their
numbers, no matter how small,
reduces the amount of food
manufactured. But because most
trees produce more food than
they need to survive, they can
tolerate some loss of leaves.
Indeed, loss of up to about half
the leaves results in little more
than reduction in growth. But
when more than half of the
leaves are eaten, not enough food
and other substances needed for
growth are produced; this
situation triggers the process of
refoliation. When all the leaves
are eaten and no food is
produced, the tree must subsist
on its reserve foods until new
leaves are formed. Gypsy moth
defoliation is especially
detrimental because it occurs at
precisely the most critical time
for the tree-when growth is
most active and when food
reserves are at their lowest
normal levels.


Tree Condition














26A 26B:.
^**


When enough leaves are eaten to
cause the tree to refoliate,
changes occur both outside and
inside the tree. After 2 to 3
weeks, buds begin to open and a
second crop of leaves develops.
These leaves are often smaller
and are a lighter green than those
produced in spring (fig. 26).
Inside the tree, defoliation and
the refoliation process have
markedly reduced the amount of
food energy reserves, energy that
the tree needs to maintain itself
during the winter dormant period
and to produce buds and twigs
in the early spring. Low energy
reserves, together with the
desiccation of immature buds
produced during refoliation, will
result in the death of buds, twigs,
and branches during winter
months.


If no defoliation occurs the
following year, most trees (except
for trees already in poor
condition) will survive and regain
their former fullness. But
defoliation, even at low levels,
can be harmful if repeated for
several years; even healthy trees
may die if they go through the
defoliation/refoliation process for
2 or 3 years in succession.

Figure 26.-Refoliated leaves of
defoliated trees (A) are usually
smaller and lighter green than
normal leaves (B).


26B







Mortality-Causing Organisms


The final blow to most defoliated
trees is dealt by opportunistic
organisms that can successfully
attack and kill trees stressed by
defoliation. One of these
organisms, the shoestring root-rot
fungus, Armillaria mellea, enters
the bark and wood of weak,
dying, or dead roots. The fungus
grows rapidly between the bark
and wood of the roots and root
collar (fig. 27) and can kill the
tree quickly. Armillaria also can
decay tissues of the roots that
store food or that absorb and
transport food, water, and
minerals. In addition, death of
small roots may start a cycle of
decline that can result in the
tree's death.

Another organism that can
invade oaks weakened by
defoliation is the twolined
chestnut borer, Agrilus bilineatus.
This insect attacks and chews
feeding tunnels under the bark of
branches and tree trunks (fig. 28).
These tunnels in the outer wood
and inner bark interfere with the
passage of food, water, and
minerals causing the death of
more branches and roots.

The combined attacks by the
shoestring fungus in the roots
and root collar and the twolined
chestnut borer in the branches
and stems usually result in tree
death. Often, attacked trees die
so rapidly, especially in late
summer, that their leaves
suddenly wilt and turn brown.


Figure 27.-Dead oak tree with
bark removed to show white
fans of the shoestring root-rot
fungus.
Figure 28.-Dead oak tree with
bark removed to show feeding
tunnels of the twolined chestnut
borer.





Managing the Gypsy Moth


The Natural Enemy Complex


There are two approaches to
preventing or alleviating the
problems of gypsy moth
invasions: One is directed against
the insect; the other is designed
to improve the growing
conditions for trees around the
home.

In addition to knowing about the
gypsy moth and the damage it
inflicts, you should be aware of
the many natural enemies that
collectively destroy it, because the
actions you select to control the
gypsy moth may also affect these
many beneficial organisms.


The natural enemy complex,
which is composed of parasites,
predators, and disease, does not
control the gypsy moth in
outbreak situations but does aid
in maintaining certain sparse
gypsy moth populations at low
levels. It may also help to extend
the period of years between
outbreaks. Disease is the major
factor in halting outbreaks, but
unfortunately this occurs only
after the full impact of gypsy
moth defoliation has been
realized.











Parasites


Parasites are living organisms that
make their homes on or in the
bodies of other living organisms
(hosts) from which they get
nourishment during at least one
stage of their life. A parasite
usually requires only a single
individual of the host species to
complete its development.

In North America, there are
about a dozen species of
parasites that attack various
gypsy moth life stages, and their
abundance varies greatly from
place to place and year to year.

Several species of small wasps
attack the various life stages of
the gypsy moth. One of the most
common species, Ooencyrtus
kuvanae, attacks the eggs
wherever they occur, resulting in
small pinholes on the surface of
the egg mass (fig. 29). Apanteles
melanoscelus attacks and kills
small larvae (fig. 30), and
Brachymeria intermedia (fig. 31)
stings gypsy moth pupae but is
most effective only when gypsy
moth populations are at
defoliating levels.

Three species of flies that are
slightly larger than the common
house fly attack large larvae and
are important parasites of the
gypsy moth. One of them,
Parasetigena agilis, lays its eggs
near the head of the larvae (fig.
32). The maggots (or larvae) of
these flies develop to maturity
within gypsy moth larvae and
pupae, leaving only the outer
shells behind (fig. 33).


Figure 29.-Weathered egg mass
showing pinholes caused by egg
parasite.
Figure 30.-Attached cocoons of
a wasp that kills young larvae.












































33


















Figure 31.-A small wasp that
stings gypsy moth pupae.
Figure 32.-Eggs of a fly
parasite attached to late-stage
larva.
Figure 33.-Maggots of parasite
fly eventually destroy the pupae,
leaving only the outer shell.












Predators


9.d
9r ^ ;'* *-< .i,^


Whereas parasites are usually
smaller than the host they attack
and develop within a single
individual, predators usually are
larger than their prey and
consume many host insects
during the course of their life.
They are very active, live longer,
and are opportunistic in that they
may prey upon a variety of
insects, depending on what is
available.

Although predators destroy many
life stages of the gypsy moth,
their importance has probably
been underestimated because they
consume their prey quickly and
leave few if any remains.
Woodland mammals can consume
large numbers of gypsy moth
larvae and pupae in forested
areas. Some mammals eat only
one life stage of gypsy moth,
while others may eat as many as


three. Some mammalian predators
of the gypsy moth include the
white-footed mouse (fig. 34),
shrews, chipmunks, voles, and
squirrels. Shrews, which are often
mistaken for mice, are voracious
insect feeders (fig. 35) that
consume their own weight in
prey each day. Unfortunately,
mice and shrews are probably
not important as predators in
suburban settings because they
are eliminated by domestic
animals such as the common cat
and because their natural habitat,
forest litter, is frequently
destroyed.
Figure 34.-White-footed mice
eating larvae.





















































Many species of birds have been
observed feeding on gypsy moth
larvae or adults. Nuthatches,
chickadees (fig. 36), towhees,
vireos, northern orioles, catbirds,
robins, and blue jays are
probably more important in
sparse gypsy moth populations.
Cuckoos (fig. 37 ) and flocking
species such as starlings, grackles,
red-winged blackbirds, and crows


may be attracted to areas where
the gypsy moth exists in large
numbers.
Figure 35.-Shorttail shrew
eating larva.
Figure 36.-The black-capped
chickadee feeds on all gypsy
moth life stages.
Figure 37.-The black-billed
cuckoo prefers hairy caterpillars
like the gypsy moth.
















































Less is known about the
importance of insect or insect-
related predators of the gypsy
moth, although more is being
learned about their importance.
Ground beetle larvae and adults
feed readily on gypsy moth
larvae and pupae (fig. 38) and
are usually most evident when
gypsy moths are numerous. These
beetles are very active and
readily climb trees in search of
their prey. Many gypsy moth
larvae and pupae that rest on or


near the ground are destroyed by
spiders (fig. 39), ants, and
harvestmen (daddy longlegs). The
collective value of these
organisms has not been widely
recognized because they are less
conspicuous than other predators,
and their activities are difficult to
monitor.
Figure 38.-This ground beetle
destroys both larvae and pupae.
Figure 39.-Many kinds of
spiders kill gypsy moths.











Disease


wa-,'
0 4 1


There are many diseases caused
by bacteria, fungi, or viruses that
kill gypsy moth larvae. Only one,
however, the nucleopolyhedrosis
virus (NPV), has a dramatic
effect on gypsy moth populations,
frequently resulting in the total
collapse of outbreaks. Virus-killed
larvae are commonly seen
hanging in an inverted V-shaped
form from trees (fig. 40); their
bodies are dark and flaccid and
contain only liquified material
composed mainly of the


infectious virus. Large numbers of
virus-killed larvae usually indicate
a general collapse caused by the
virus.
Figure 40.-Larva killed by
disease caused by a natural
virus.








Guidelines for Tree Survival

Maintain Good Conditions for
Growing Trees


Trees that are stressed are more
vulnerable to defoliation and the
opportunistic organisms that
frequently attack them, so efforts
should be made to keep trees in
a good state of health or vigor.
Nearly all the recommendations
discussed here emphasize the
importance of maintaining good
soil nutrient and moisture
relationships.

* Keep soil conditions favorable
for the development and survival
of the tree's fine feeder root
system. Construction activities
such as cutting and filling,
installing utility and septic tank
field lines, changing grades,
paving, and cutting down the
surrounding forest may have
harmful effects on soil/moisture
relations. A general rule is to do
no more than is necessary.

* In wooded backyards, or in
yards where lawns and forests
meet, an attempt should be made
to keep the forest floor surface
as natural as possible (fig. 41).
Because oaks thrive under acid
soil conditions, removal of their
organic acid-rich leaf litter can


be harmful. Layers of natural leaf
litter help prevent drying out
surface soil layers that contain
the bulk of the tree's feeder roots
and provide a natural habitat for
predators such as mice and
shrews that prey upon gypsy
moth larvae and pupae.

* Growth conditions for isolated
trees planted on lawns can be
enhanced by encircling them with
mulch or ground cover plants
(when practical) out to an area
delimited by the outer branches.
A dense grass layer over feeder
roots causes severe competition
for moisture and nutrients.
Applications of lime or weed
killers around forest trees can
seriously damage shallow tree
roots.

* In times of drought, stressed
individual trees can also benefit
from watering, fertilizing, and
judicious pruning to thin the tree
tops and reduce moisture
demands on the roots.
Figure 41.-Wooded areas
adjacent to lawns should be
kept in a natural state.











Discourage Survival and Destroy Life
Stages


S42


There are other practices that
directly affect the insect itself,
especially in sparse populations,
and that should be considered as
part of a total preventive
program around the home.

* Remove objects around the
yard that provide shelter for
gypsy moth larvae and pupae
and increase their chances for
survival. These include natural
objects such as bark flaps, dead
branches (fig. 42) and trees,
stumps, and debris on the ground
such as boxes, cans, or old tires.

* Diversify composition of trees
and plants or encourage those
species that are known to be
unpopular with the insect. Species
such as tulip or yellow poplar,
honeylocust, ash, maple, hickory,
dogwood, mountain ash, and
many conifers can be
incorporated into a landscaping


plan that will make your
property less susceptible to gypsy
moth and other defoliators as
well. Check first with your
nurseryman, arborist, or county
cooperative extension agent to
select those tree species that are
most compatible with your
particular climate and soil and
site situation.

* During the winter months,
remove and destroy egg masses
that are found on or around
homes and premises. Carefully
inspect buildings such as
toolsheds, garages, and tree
houses, as well as stone walls,
woodpiles, and fencing for hidden
egg masses. Check lawn chairs and
other yard equipment for egg
masses before storing them away
for the winter.
Figure 42.-Dead branches and
bark flaps should be removed.













Sb* Place burlap on trees, especially
* oaks, and destroy gypsy moth
larvae and pupae that hide
beneath during daylight hours
(fig. 43). The burlap also aids in
-. keeping tabs on numbers of the
insect and encourages activity by
resident parasites and predators
that search out protected
locations for larvae and pupae.

Placing a band of sticky
material (such as grease, tar, or
other petroleum product) around
trees to entrap gypsy moth larvae
4, :is not encouraged. These
materials can cause injury
(swelling and cankering) on thin-
barked trees such as maples and
young oaks (fig. 44).

















Figure 43.-Many gypsy moth
larvae resting beneath burlap
skirt.
Figure 44.-This maple was
disfigured where a homeowner
placed a band of sticky material
around the tree.











Protect Foliage From Defoliation

Under normal circumstances,
when few insects are observed,
annual protective spraying of
pesticides on trees and shrubs
around the home to control the
gypsy moth is probably not
justified and may have an
adverse effect on the insect's
natural enemy complex. Your
decision to use or not use
pesticides should be influenced by
environment, economics, and
practical concerns as they relate
to the following:

Number of and kind of trees-Is
there a large proportion of
preferred hosts on your property?

Tree condition-Are your trees
showing signs of decline (dead or
dying branches) especially near
the top?

Proximity to other areas of
infestation-Is your property
located adjacent to areas heavily
infested with gypsy moth?
(Windblown first-stage larvae and
migrating late-stage larvae in
search of food can infest your
property.)

History of past infestation-Were
your trees recently defoliated by
gypsy moth or other insects?


Indications of anticipated severity-
Have you observed gypsy moth
larvae feeding on your trees,
resting under bark flaps, burlap
bands, or in other protected
locations? Are gypsy moth larvae
numerous enough to be
considered a nusiance to you on
your property?

If the answer to three or more of
these questions is yes, then you
should consider the use of a
chemical or biological pesticide to
protect foliage of your trees and
to reduce the number of gypsy
moths. There are several
pesticides registered for control of
the gypsy moth. To obtain the
most current recommendations on
pesticides and their application in
your area, you should contact a
county cooperative extension
agent, State entomologist,
nurseryman, arborist, city or State
forester, or specialists at your
State university or agricultural
experiment station.





Acknowledgments


Figure 4 is used through the
courtesy of the Connecticut
Agricultural Experiment Station,
New Haven.

We thank the Encyclopaedia
Britannica Educational
Corporation for kindly allowing
the use of figures 36 and 37,
which were copyrighted 1962-64.


These publications may be of
interest to homeowners
confronted with the gypsy moth
problem:

Campbell, R. W. 1975. The gypsy
moth and its natural enemies.
U.S. Dep. Agric., Agric. Info.
Bull. 381.

McManus, M. L., and R. T.
Zerillo. 1979. The gypsy moth:
An illustrated biography. U. S.
Dep. Agric., Home and Garden
Bull. 225.

Smith, H. R., and R. A.
Lautenschlager. 1978. Predators of
the gypsy moth. U. S. Dep.
Agric., Agric. Handb. 534.

Talerico, R. L. 1978. Major
hardwood defoliators of the
Eastern United States. U. S. Dep.
Agric., Home and Garden Bull.
224.

Wargo, P. M. 1978. Defoliation
by the gypsy moth: How it hurts
your tree. U. S. Dep. Agric.
Home and Garden Bull. 223.










Issued August 1979
Available from the Superintendent
of Documents
U. S. Government Printing Office
Washington, D.C. 20402
Stock No. 001-000-03950-4

* U.S. GOVERNMENT PRINTING OFFICE : 1979 0-275-407


References







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