Gypsy Moths in Fairfax County
In 1869, the gypsy moth, Lymantria dispar, escaped from a Massachusetts lab and became established in North America. It continues to be a serious insect threat to trees and shrubs in the United States.
Gypsy moth caterpillars feed on leaves of forest, shade, ornamental, fruit trees and shrubs. Large numbers of them can defoliate a tree by eating 60 to 100 percent of its leaves. Hardwood trees such as oak and hickory may be killed by two or more defoliations, but a single defoliation may kill some evergreens. Some of the gypsy moth's favorite host trees are oak, hickory, beech, birch, willow and spruce.
What do I look for?
Gypsy Moth Suppression Program
Fairfax County Urban Foresters monitor gypsy moth populations every summer and fall by counting gypsy moth egg masses throughout the county. This helps determine where active infestations are occurring. If serious infestations are found, the Forest Pest Branch develops a caterpillar suppression program. Homeowners and residents residing in or near any proposed treatment areas are notified by mail in advance of a voluntary spray program. The material used for the suppression program is Bacillus thuringiensis kurstaki, a pesticide registered with the U.S. Environmental Protection Agency for use in forested residential areas.
What can you do?
You can help detect gypsy moth infestations by keeping an eye out for the caterpillars in the spring and searching your property for egg masses later in the year. Female moths will lay their eggs starting in mid-July. Egg masses are tan colored and can be seen on tree trunks and undersides of branches or in sheltered areas, such as under the eaves of houses or in wood piles.
Report egg masses in your neighborhood
The Forest Pest Branch needs your help finding the next big infestation of gypsy moths. Become a part of a volunteer group to monitor for egg masses on public or park land by visiting Fairfax County Gypsy Moth Volunteer Monitoring Web page.
To report gypsy moth egg masses in your neighborhood, fill out the online form.
Scrape and Destroy
Scraping egg masses into a container of soapy water or bleach solution is an easy way to kill unwanted gypsy moths.