17 Wisconsin counties to be treated for spongy moth

A gypsy moth caterpillar at work eating leaves.
A gypsy moth caterpillar at work eating leaves.(Bill McNee, DNR)
Published: May. 2, 2022 at 2:46 PM CDT
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MADISON, Wis. (WMTV) - 17 Wisconsin counties will begin to get treated for spongy moth starting in mid to late May.

Spongy moth, formerly known as gypsy moth are an invasive species that defoliate many kinds of trees and plants which can cause them stress and potentially death. In an attempt to slow their spread, treatment efforts will be focused in western Wisconsin, where spongy moth populations are beginning to build.

“Where this insect is established, it has been a periodic public nuisance and damaging forestry pest,” said Christopher Foelker, Spongy Moth Program Manager.

The Wisconsin Department of Agriculture, Trade, and Consumer production will be treating the following counties aerially: Barron, Bayfield, Buffalo, Burnett, Chippewa, Crawford, Dunn, Eau Claire, Grant, La Crosse, Lafayette, Pepin, Rusk, Sawyer, Trempealeau, Vernon, and Washburn.

Small, yellow planes will be used to treat these areas. Residents can expect to see and hear loud, low-flying planes as early as sunrise and continue on until early afternoon.

“DATCP will be conducting aerial treatments, which are the most efficient and effective method to delay the impacts associated with spongy moth outbreaks,” Foelker said.

Treatments are expected to begin in southern Wisconsin early to mid-May and end in northern Wisconsin mid-July. Spraying begins shortly after the caterpillars hatch and depends on favorable weather: calm, with no precipitation or high humidity.

In mid-May to early June, the planes will spray Bacillus thuringiensis var. kurstaki, a naturally occurring soil bacteria that kills spongy moth caterpillars feeding on foliage, according to the news release. Btk is not toxic to people, bees, pets, or other animals.

In late June to mid-July, planes will spray an organic, biodegradable mating disruptor containing a spongy moth pheromone. This inhibits the adult male spongy moth’s ability to locate females.

Maps of the treatment areas are available.

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