ASK THE CHALET PROS

January 10, 2009
Q: I've heard gypsy moths are in our area now. Why are they so bad?

A: Gypsy Moths are now common in Cook, Lake, McHenry and DuPage counties and their potential for destruction of trees and shrubs is great. A single caterpillar (larva) can eat up to one square foot of foliage per day…they feed for 4-6 weeks during May and June. While GM prefers oak, apple, crabapple, and white birch, it will feed on about 500 different kinds of trees and shrubs and that includes evergreens (as a last resort).
Female gypsy moths with egg masses
Earlier this year we had our first confirmed GM caterpillars brought to our Wilmette store primarily from Glenview residents. Our landscape designers also reported concentrations in Lake County during visits to clients. In July these destructive caterpillars have turned into moths and are laying their egg masses. Here are things that to do right now to reduce populations if you find egg masses on your property.

GM females lay their eggs on any convenient surface, including fences, homes, vehicles as well as tree trunks and branches. The egg masses are raised, tear-dropped shaped forms covered with tan or buff colored hairs. They range from ¾" to 2” long and may contain up to a thousand eggs in each mass.
What can you do if you find the egg masses on your property? If you are in quarantine area (as most of us are now) no reporting to any governmental agency is necessary.

Egg masses may be suffocated in place with a horticultural or soybean oil-based insecticide (always pretest surfaces for staining). Use a trowel or other sharp-edged object to scrape the “nests” off the surface you found them on. Do not handle caterpillars or egg masses with bare hands. The hairs may cause a mild allergic reaction. Wear gloves or use a putty knife to dislodge them. You may then:
  • Put them in a microwave-safe container and “nuke them” them on high for 2 minutes or
  • Drown them in soapy water for 2 days or
  • Kill them by crushing or
  • Bury them under 6-12” of soil.
Don’t just knock them off to the ground. They will survive and hatch in the spring.
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