Fact Sheet
Gypsy Moth
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The North American strain of Gypsy moth is currently established in parts
of eastern North America. The female moth is flightless. Infestations normally
spread slowly, with spring breezes blowing young larvae a few kilometres. Long distance
expansion occurs as egg masses are carried on goods moved to new areas.LIFE CYCLE
The adult female lays eggs in masses covered by buff hairs from her abdomen. The egg
masses resemble small pieces of chamois on tree trunks and the undersides of branches,
under loose bark and in tree cavities. They also cling to things under or near trees, such
as outdoor furniture, boats, trailers, vehicles, toys, camping equipment, piles of wood
and lumber.
In the spring, numerous tiny caterpillars hatch from the eggs. By midsummer they are
fully grown, about six to seven centimetres long, dark and quite hairy. Each has a double
row of tubercules along its back, usually five pairs of blue and six of red (but sometimes
all black or blue).
The pupae are dark reddish brown, usually with a few yellowish hairs. You can easily
tell male from female pupae as the female ones are much larger.
Adults emerge during the latter part of July and on through August. The male (a strong
flier) is brown, with a small body and well-developed wings. The female is white with
black markings on her wings, and much larger. Despite her well-developed wings, she cannot
fly and moves only a short distance from her pupal case—she relies on a scent to
attract a male. After mating, she lays her eggs, which pass the winter and hatch the
following spring.
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PREFERRED HABITAT
The Gypsy moth has a wide host range which includes native shade trees, as well as Garry oak and valuable ornamentals trees. Should the Gypsy moth
become established, trees will be stripped of their leaves in midsummer.
Such defoliation could undermine the intrinsic recreational/health and
wildlife habitat values that these trees provide. Local parks could also be jeopardized.
CONSEQUENCES OF INFESTATIONS
A Gypsy moth infestation on Vancouver Island may result in B.C.’s major trading
partners both inside and outside Canada's
placing restrictions on exported lumber, nursery products and other products leaving the
area.
This moth will also impact agriculture as it will eat the leaves of fruit trees,
blueberries and hazelnuts. Apple leaves are an excellent host. The Gypsy moth is therefore
a direct threat to major B.C. fruit producers.
The Gypsy moth may also cause a minor human health hazard because some individuals are
allergic to the hairs shed by the caterpillars.
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ERADICATION
The reasons for eliminating the Gypsy moth are numerous. Eradication can be
accomplished by an integrated approach involving the destruction of eggs, the application
of a biological control agent (Btk) and by trapping adults in the summer.
Spray programs usually start shortly after the Gypsy moth caterpillars hatch from
their eggs. This will probably start in mid-April and continue into mid-June.
The Gypsy moth caterpillars hatch over several weeks. The Btk biological product used
in the aerial spray campaign will break down quickly in the environment and must be
reapplied. This is because the caterpillars must be in an early larval stage for the Btk
to work. Unfortunately, not all caterpillars hatch at the same time. Because the product
breaks down quickly, it will not be available to caterpillars that hatch after the first
spraying, unless several applications are made.
The product being used is
Bacillus thuringiensis variety
kurstaki (Btk). Btk is not harmful to humans, birds or fish. It biodegrades in three
to seven days. To work, the caterpillars must eat the Btk. The human stomach is too acidic
for the Btk and humans do not have the same enzymes that are found in caterpillars. Btk is
used regularly by organic gardeners in growing food.
Should you locate Gypsy moth eggs or require further information, please contact the
nearest Ministry of
Forests and Range office.
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Back to the Gypsy
Moth Homepage
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Contact Tim Ebata
if you have comments on the presentation of this information.
BC Ministry of Forests and Range
Forest Practices Branch
P.O. Box 9513 Stn. Prov. Gov.
Victoria, BC
V8W 9C2
Section phone: (250) 387-8739
Section fax: (250) 387-2136
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