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The 2008 gypsy moth trapping season in Wisconsin has ended, and based on the number of moths caught, it may mean more required treatment in 2009.
Trapping for gypsy moths is not used as a method of population control; it is a measuring tool. It shows where the moths are and the extent of its population.
A total of 385,554 male gypsy moths were caught in 2008, surpassing last year’s total of 293,160 moths. Approximately 30,000 traps were set in 52 counties this summer as part of the Wisconsin Department of Agriculture, Trade and Consumer Protection’s Gypsy Moth Slow the Spread Program.
Trapping data helps determine potential sites for egg mass surveys and next year’s aerial spray treatments. Earlier this year, a total of 79,929 acres in 13 counties received treatment. Treatment sites for 2009 are yet to be determined.
There is no definitive reason for the increase of moths, but one possibility may be the natural cycle of moth populations.
Other possible explanations include favorable weather conditions, better trapping lures, the natural progression of the moth’s movement westward and larval drift. A high instance of female larvae mortality might also be a cause. The lack of female moths may force male moths to fly farther in search for a female moth.
From now until spring, people can help decrease the number of next year’s caterpillars by treating or removing egg masses. A gypsy moth egg mass is tan, oval or tear-shaped and a little bigger than a quarter. It is flat and has a velvety texture.
Egg masses can be found on trees, vehicles, fences, playground equipment, buildings and any outdoor item. An egg mass can hold 500 to 1,000 eggs.
Egg masses can be scraped off with a putty knife, stiff brush or similar hand tool and dropped into a container of warm, soapy water. Let them soak for a couple of days and discard them in the trash. Horticultural oil also can be sprayed onto egg masses. Crushing the egg masses will not destroy the eggs.
The gypsy moth is an invasive pest that has been spreading westward since its introduction in 1869. Gypsy moth caterpillars feed on many species of trees and shrubs, especially oaks, and can cause defoliation when feeding in large numbers.
As moths, the males concentrate on finding a female to mate. Females lay an egg mass, and the moths die. Caterpillars then hatch the following spring, and the cycle starts again.
For more information, call the gypsy moth toll-free number 1-800-642-MOTH (1-800-642-6684) or log onto
www.gypsymoth.wi.gov.
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