Gypsy Moths
Last Review/Updated: February 14, 2006
Gypsy moth, Lymantria dispar (L.) is a member of the Lymantriidae family and is one of the most serious introduced pests of trees in eastern Canada. The adult female is a large white moth and the adult male is a smaller brownish-tan moth. The larvae have five pairs of blue and six pairs of red spots along their hairy black bodies.
Gypsy moth has not become established in Alberta. It prefers to feed on the foliage of oak trees, which are not native to Alberta's forest. However, it can attack and kill other deciduous tree species in Alberta. It is a serious threat to our forests.
There have been some reports of gypsy moths found on Christmas trees imported into Alberta. Alberta Sustainable Resource Development is working cooperatively with the Canadian Food Inspection Agency to detect this pest in Alberta's forests.
For Canada-wide gypsy moth information, please see the Canadian Food Inspection Agency (Off-site).
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Current Maps
There is currently no new ground or aerial survey information. For historical information, please see Historical Conditions.
Moratoriums
There are currently no pest moratoriums in Alberta. Check this page regularly for updates especially in the spring and summer.
Commonly Asked Questions
- How was the gypsy moth introduced into Canada?
- What is the difference between European and Asian gypsy moth?
- How do we recognize the gypsy moth?
- What tree species does it usually attack?
- So why is there much concern about the gypsy moth compared to other forest insects?
- Has gypsy moth been found in Alberta?
- If European gypsy moth is in eastern Canada, why should we worry about it in Alberta?
- What can you do to keep the gypsy moth out of Alberta?
- What are we doing to keep the gypsy moth out of Alberta?
How was the gypsy moth introduced into Canada?
Two different forms or strains of gypsy moth (Lymantria dispar (L.)) have been found in Canada: the European form and Asian form.
European gypsy moth
In 1869, a French naturalist brought the European gypsy moth into the state of Massachusetts for breeding experiments. Some moths accidentally escaped and established in the surrounding area. Now this pest is a severe defoliator of deciduous trees in eastern Canada and the northeastern quarter of the United States and is moving west.
Asian gypsy moth
The Asian gypsy moth is native to the Russian Far East. Though this form of gypsy moth has not established in Canada, there have been several occasions when it was accidentally introduced into the west coast of Canada and the US. Asian gypsy moths were first reported on Soviet ships in British Columbia in 1979 and then again in 1989, 1990 and 1991. In 1992, a decision was made to protect the Vancouver harbour area from Asian gypsy moth by an extensive spray program. Since then continued monitoring and control, measures have prevented its establishment in British Columbia.
What is the difference between European and Asian gypsy moth?
The two forms of gypsy moth are generally very similar in appearance. However, the Asian gypsy moth is larger than the European form and it can fly, making it easier to disperse. Also, it tends to prefer more types of trees than the European strain of gypsy moth and the egg masses may be able to withstand colder winter temperatures. The Asian gypsy moth has only been found in British Columbia and is not yet established. The European gypsy moth is established in eastern Canada and the northeastern quarter of the United States.
How do we recognize the gypsy moth?
Egg masses (2-4 cm long) are buff coloured and covered with fine hairs giving them the appearance of small pieces of chamois. Egg masses are generally laid on, in or under, outdoor furniture, recreational vehicles, camping equipment etc.
Small caterpillars are seen in May and grow to large caterpillars (6-7 cm long) by late June. They have five pairs of blue and six pairs of red spots along their hairy black bodies. After the feeding period ending early August, caterpillars pupate in sheltered places. Adult moths emerge in late July to early August. Females are white and are larger than the brown males. Both have blackish markings on the wings but only males can fly.
What tree species does it usually attack?
Though gypsy moth caterpillars prefer to eat oak, birch, willow and trembling aspen, they can feed on the leaves of hundreds of species of plants, including conifers.
Why is there much concern about the gypsy moth compared to other forest insects?
- In the gypsy moth's native land there are about 200 species of parasites and predators that keep it in check. Here, in North America there are only 43 such species.
- A single gypsy moth can produce up to 1200 eggs!
- In high populations, gypsy moth caterpillars can be a nuisance around homeowner properties.
- Caterpillars can eat up to 90 cm² of leaf tissue per day.
- During severe infestations, gypsy moth caterpillars will feed on any tree species.
Has gypsy moth been found in Alberta?
In 1991, Christmas trees infested with European gypsy moth egg masses were imported into Calgary and Edmonton. Fortunately, appropriate action was taken and this accident did not become a problem.
If European gypsy moth is in eastern Canada, why should we worry about it in Alberta?
Though the female moth does not fly, humans can facilitate the movement of the insect across the country! Caterpillars of the gypsy moth can pupate or the moths can lay eggs on items such as firewood, trucks, outdoor furniture, toys and camping equipment. So it just takes one egg mass on a car of a family vacationing or moving to Alberta from an area of infestation to advance the spread!
What can you do to keep the gypsy moth out of Alberta?
If you have just moved to Alberta from eastern Canada or from the northeastern quarter of the United States, you should inspect all your outdoor equipment and furniture, and recreational vehicles for egg masses or pupae. If you find gypsy moth, scrap it off and dispose of it in a sealed container. If you would like further information, visit the Canadian Food Inspection Agency (Off-site) website or contact them at 1-800-442-2342.
What are we doing to keep the gypsy moth out of Alberta?
A restriction has been made on the movement of nursery stock, firewood, or timber products from regions of infestation.
Alberta Sustainable Resource Development is helping to prevent dispersal of egg masses and pupae found on recreational vehicles, etc. through education and involvement of the public.
Alberta Sustainable Resource Development assists the Canadian Food Inspection Agency by setting up delta traps with the female moth's sex scent (pheromone) to detect the presence of gypsy moth in the forested areas of Alberta. Established in areas of high public use in the summer, these pheromone traps are used to lure gypsy moth males in the area. If a moth is captured, the site can be monitored closely and appropriate action can be taken, if necessary.
