Forestry Branch
Gypsy Moth
What is Gypsy moth?
Gypsy moth in Manitoba
Life cycle
Damage
Identification
How does it spread?
What can you do?
Gypsy Moth Management Programs
What is Gypsy moth?
European gypsy moth (Lymantria dispar) is an invasive forest pest from Europe and Asia that feeds on leaves during the caterpillar (larval) stage. Gypsy moth prefers oak, poplar, elm, maple and birch but will also feed on other broadleaved trees, shrubs and conifers. Repeated defoliation by this insect can kill trees. Gypsy moth can have negative ecological and socio-economic impacts and is an unwanted pest worldwide. It was unintentionally introduced to Massachusetts in 1869 and is now established in eastern Canada. Gypsy moth is not established in Manitoba.
Gypsy moth can cause significant damage to the broadleaved forests in eastern North America. The caterpillars defoliate large areas of primarily oak forests in southern Ontario, Quebec and the Maritimes. Since its introduction, it has been steadily moving westward. It has now reached western Wisconsin and is close to Minnesota.
Caterpillars feeding on oak leaves |
Defoliated forests by Gypsy moth |
Gypsy Moth in Manitoba
Gypsy moth has been found occasionally in Manitoba in small numbers. A small population of gypsy moth became established in two areas south of Winnipeg. These populations were successfully eradicated in 2009.
The Canadian Food Inspection Agency (CFIA) is responsible for monitoring and regulating gypsy moth in Canada. The CFIA monitors gypsy moth annually through the trapping of adult male moths. Manitoba Conservation and Water Stewardship, Forestry Branch assists the CFIA in their monitoring efforts.
- There is one generation per year in Manitoba.
- Gypsy moth overwinters in the egg stage and hatches in spring when leaves are developing on trees.
- The young caterpillars crawl up host plants and begin feeding on the new leaves. They go through several growth stages (instars) and will feed for six to eight weeks. Most of the damage is done at the later growth stages..
- The older/larger caterpillars will feed at night and crawl to the ground to find shady spots during the day.
- Feeding continues until early July, at which time the fully grown caterpillars will seek a shady spot to pupate.
- Moths emerge in late July and August. Moths do not feed. Only the males fly as females are not capable of flight.
- After mating in August, the female lays eggs in a single oval buff-coloured mass.
- Egg masses can be found attached to various items in sheltered places, such as tree bark, fences, outdoor furniture and vehicles.
Gypsy moths and egg masses
- The caterpillars of the gypsy moth feed on the leaves of more than 450 different types (species) of trees and shrubs.
- In outbreak situations, trees may be nearly completely stripped of their leaves.
- This loss of foliage can stress the trees making them vulnerable to attack by other insects and diseases. Repeated severe defoliation can cause the trees to die.
- Trees that have had their leaves removed do not provide the shade they normally do, and all of the frass (fecal matter) created by the caterpillars is messy and unpleasant.
- The adult female moth is white with black zigzag markings and has a wingspan of 37 to 62mm (figure 1).
- The adult male moth is tan to brown with black markings and has a wingspan of 37 to 50 mm (figure 2).
- The caterpillars go through several growth stages and can grow to be as long as 60 mm.
- Caterpillars can be identified by two distinct rows of blue and red spots along their back (figure 3).
- Egg masses are 15 to 40 mm long and each mass may contain as many as 1000 eggs. The masses are usually oval shaped, slightly raised and are a buff beige colour that fades with age (figure 4).
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Figure 1: Female Gypsy Moth |
Figure 2: Male Gypsy Moth |
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Figure 3: Gypsy Moth Larva |
Figure 4: Gypsy Moth Egg Mass |
- Gypsy moths can spread into new areas through natural migration, household moves and recreational travel.
- Young caterpillars are spread by being windblown on their silken threads to neighbouring trees.
- Older caterpillars will migrate to new areas once food supplies have been exhausted.
- Long distance spread occurs through the movement of their egg masses attached to such objects as vehicles, trailers, boats, outdoor furniture and equipment - this is likely the major pathway for gypsy moth entering into Manitoba.
Most of eastern North America is infested with gypsy moth. Before returning to Manitoba from any of these states or provinces, please inspect your camping equipment and recreational vehicles for the presence of gypsy moth egg masses. Also, leave any firewood behind. Firewood can spread gypsy moth and other harmful pests.
Homeowners
Be vigilant. Inspect your property and surrounding area for gypsy moth egg masses in early spring. Look on tree trunks, firewood piles, in bird houses, under patio furniture, BBQ’s, under rocks or anything else that is stored or piled in your yard. If you find any egg masses, leave them intact and contact Manitoba Conservation and Water Stewardship, Forestry Branch (Tree Line 204-945-7866).
Nursery owners
Inspection should include plant material, containers, soil, pots, etc. See the Canadian Food Inspection Agency website for more information Canadian Food Inspection Agency (CFIA) .
Gypsy moth egg masses on tree trunk
Inspection for Gypsy moth egg masses
Photos courtesy of Manitoba Conservation, USDA Forest Service (Mark Robinson, John H. Ghent), USDA Aphis PPQ Archive, Tim Tigner.
