Forestry Branch
Gypsy Moth in Manitoba
What is Gypsy moth?
Life cycle
Damage
Identification
How does it spread?
What can you do?
Health Information
Gypsy Moth in Manitoba
The Canadian Food Inspection Agency (CFIA) has been monitoring for European Gypsy moth (Lymantria dispar) in Manitoba through the trapping of adult male moths. While some moths have been trapped periodically in the province over the years, high male moth captures in the La Salle area in 2006 prompted more intensive monitoring in this area in co-operation with Manitoba Conservation.
In 2007, the number of adult male moths captured increased in the La Salle and St. Germain areas. As a result, an egg mass survey was conducted, and several egg masses were found and destroyed in the La Salle area. In 2008, the number of adult male moths captured increased again and another egg mass survey was conducted. Many more egg masses were found and destroyed in the La Salle area and some in the St. Germain area. The increase in male moth captures and egg masses found over the past two years indicates a Gypsy moth population could be establishing in these two areas.
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What is Gypsy moth?
Gypsy moth is an invasive forest pest (native of Europe, North Africa and Asia) that eats leaves during the caterpillar (larval) stage. Gypsy moth will feed on hardwoods or conifers and prefer oak, poplar, elm, maple and birch. Repeated feeding by this insect can kill trees. It was first introduced to North America in 1869 and is established in Canada in Ontario, Quebec and the Maritimes.
Examples of damage caused by Gypsy Moth
- There is one generation per year.
- Gypsy moth overwinters in the egg stage and hatch in spring when leaves are developing on the 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. The most damage is done in the later caterpillar stages.
- The later caterpillar stages will move or migrate to the ground to find more food, shady spots during the day and sheltered areas in which to pupate.
- Feeding continues until early July, and then the caterpillars will pupate.
- Moths emerge in late July and August (they do not eat). Only the males fly. After mating, the females lay egg masses in August.
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.
- Trees may be nearly completely stripped of their leaves.
- This loss of foliage can stress the trees leaving them vulnerable to attack by other insects and diseases. Repeated severe feeding by the Gypsy moth can cause the tree 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 aesthetically displeasing.
- The hairs released into the air by the Gypsy moth can cause respiratory problems in some individuals.
- The adult female moth is mottled 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 (instars) and can grow to be as long as 60 mm and have two rows of spots along their back (blue and red) (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 (average about five km a year but can be further). The young caterpillars are blown to neighbouring trees on silken threads and older caterpillars will migrate to new areas once food supplies have been exhausted.
- The Gypsy moth may also spread through the long distance movement of their egg masses, which can be laid on a variety of surfaces, including vehicles, trailers, boats and outdoor furniture and equipment.
- Be vigilant. Inspect your property and surrounding area for egg masses of the Gypsy moth before leaves develop on the trees. Look on tree trunks, firewood piles, in bird houses, under patio furniture, BBQ’s, under rocks or anything that is stored or piled in your yard. If you find any egg masses, leave them intact and contact Manitoba Conservation Forestry Branch or the Canadian Food Inspection Agency (CFIA) so we may collect them from your property.
Gypsy moth egg masses on tree trunk
When travelling by car, truck or recreational vehicle to eastern Canada or to the Great Lakes area and northeastern United States during August and September:
- Inspect on and underneath your vehicle, trailers, cargo etc. for Gypsy moth egg masses. Remove and destroy any that are found before returning to Manitoba. Gypsy moth has become established in the southern areas of Ontario, Quebec, New Brunswick and Nova Scotia plus Wisconsin to Maine and south to Virginia.
Inspection for Gypsy moth egg masses
Control Zones 2009
Open houses were held in La Salle (April 14) and St. Germain (April 15) to discuss Manitoba Conservation’s proposed management plans.
(Updated at 6:53 am on Thursday, June 25, 2009)
Manitoba Conservation has conducted aerial applications using the biological insecticide Foray 48B, containing Bacillus thuringiensis kurstaki (Btk), to control Gypsy moth. The formulation that was used, Foray 48B, is Certified Organic and listed with the Organic Materials Review Institute, for use in organic production and food processing. Portions of St. Germain and St. Norbert were treated aerially, as well as the Kingswood Golf Course and subdivision, which is found in the Rural Municipality of Macdonald. All three of the proposed aerial applications have been completed.
The first aerial application, using the biological insecticide Foray 48B (Bacillus thuringiensis kurstaki), was successfully completed between the hours of 6:00 am and 7:00 am, on Tuesday, June 16, 2009.
The second aerial application, using the biological insecticide Foray 48B (Bacillus thuringiensis kurstaki), was successfully completed between the hours of 5:15 am and 6:15 am, on Friday, June 19, 2009.
The third aerial application, using the biological insecticide Foray 48B (Bacillus thuringiensis kurstaki), originally scheduled for Tuesday, June 23, 2009, between the hours of 5:00 am and 8:30 am, was cancelled due to high winds. The third application was then rescheduled for Wednesday, June 24, 2009, between the hours of 5:00 am and 8:30 am. This too was cancelled due to high winds.
The third and final aerial application, using the biological insecticide Foray 48B (Bacillus thuringiensis kurstaki), was successfully completed between the hours of 5:15 am and 6:15 am, on Thursday, June 25, 2009.
Pheromone trapping for adult moths will be conducted this summer within the spray block areas to monitor treatment efficacy. Trapping results will be made available on the CFIA site.
Health Canada indicates that “Btk poses little threat to human health either through handling products directly or through indirect exposure such as during a spray program…Studies have shown that even if Btk spores are ingested or inhaled, they are eliminated without any adverse health effects.” For more information, please contact Health Links–Info Santé at 788‑8200 or 1-888-315-9257 (toll-free) or view the Health Canada fact sheet.
Links
Canadian Food Inspection Agency (CFIA)
Canadian Forest Service
United States Department of Agriculture, Animal and Plant Health Inspection (USDA APHIS)
Photos courtesy of Manitoba Conservation, USDA Forest Service (Mark Robinson, John H. Ghent), USDA Aphis PPQ Archive, Tim Tigner
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