Beginning in early to mid-May, the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) plans to treat 14 western Wisconsin counties for gypsy moth. Residents can expect to see and hear loud, low-flying planes as early as sunrise.
Small, yellow planes will be treating for invasive gypsy moth caterpillars. These non-native pests defoliate many kinds of trees and plants during their caterpillar stage, causing tree stress and potentially tree death. In an attempt to slow their spread, treatment efforts will be focused in western Wisconsin, where gypsy moth populations are low or beginning to build.
“The aerial treatments the department will be conducting are the most efficient and effective method to delay the impacts associated with gypsy moth outbreaks,” says Christopher Foelker, DATCP Gypsy Moth Program Manager. “Where this insect is well-established, it has been a periodic public nuisance and damaging forestry pest.”
The harmful effects of gypsy moths include the cost of removing dead trees and potential loss of property value. Caterpillars shed their skins several times as they feed, and these bristly skins can also irritate the eyes, skin, and respiratory system in humans.
DATCP will be treating in the following counties in 2021: Barron, Chippewa, Crawford, Douglas, Dunn, Grant, Green, Iowa, La Crosse, Lafayette, Rusk, Trempealeau, Vernon, and Washburn.
Treatments are expected to begin in southern Wisconsin in early to mid-May and end in northern Wisconsin mid-July. Maps of treatment areas are available at https://gmaerialspray.wi.gov. Spraying will begin as caterpillars hatch, and depends on favorable weather – calm, with high humidity and no precipitation. Planes may start applying treatments as early as 5 a.m., flying just above treetops over treatment sites, and continue until finished or as long as weather conditions remain favorable. Spraying may last into the late morning or early afternoon.
In mid-May to early June, the planes will spray Bacillus thuringiensis var. kurstaki (Btk), targeting gypsy moth caterpillars. Btk is a naturally-occurring soil bacteria that kills gypsy moth caterpillars feeding on canopy foliage. Btk is not toxic to people, bees, pets, or other animals; however, some people with severe allergies may wish to stay indoors during nearby treatment applications. Btk is used in certified organic food production.
In late June to mid-July, planes will spray an organic, biodegradable mating disruptor containing gypsy moth pheromone, targeting adult male moths which inhibits the adult male gypsy moth’s ability to locate females.
To receive email notifications about treatment plans, sign up at https://gmaerialspray.wi.gov. To hear a recorded message detailing plans day to day, call 1-800-642-MOTH (6684).