The Gypsy Moth (Lymantria dispar dispar) was introduced to North America from France by E.L Trouvelot in 1869 who had hopes of breeding a silk-spinning caterpillar that was more resistant to disease than the domesticated silkworm. Unfortunately, the caterpillars escaped into his backyard. About 10 years later, they began to appear in large swarms, and by the late 1880s they were causing severe defoliation in the area. Since then the Gypsy Moth has become one of the most destructive pests of hardwood trees in the eastern U.S.
The adult female moths emerged from their pupae this summer. With a life span of one week, the adults do not feed; they do, however, mate and lay eggs. Although the female moth has fully formed wings, she cannot fly. She emits pheromones that attract males, mates and then lays a cluster of 75-1,000 eggs close to where she pupated. She then covers them with buff-colored, hairlike setae from her abdomen, which serve as protection from predators and parasites. The eggs overwinter and hatch in the spring. The larvae have a voracious appetite and feed on more than 300 species of trees and shrubs.
Gypsy Moth egg masses appear to be prolific this fall, perhaps because there has been no significant wet weather to fuel the fungus (Entomophaga maimaiga) that feeds on the Gypsy Moth. While there are other natural controls for Gypsy Moths (birds, squirrels, mice, etc.) they don’t prevent infestations. If you wish to rid your woodlot of these caterpillars, you can remove the egg masses and pour boiling water over them. Scraping the eggs onto the ground is less effective as they can survive temperatures of 20°- 30°F. degrees below zero.
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