MONROE — Aerial spraying for invasive gypsy moths is planned to begin May 20 in 18 western Wisconsin counties, including Green and Lafayette, according to the agency in charge of the spraying, the Wisconsin Department of Agriculture, Trade and Consumer Protection.
In Green County, sprayers will target a block of land that includes the city of Monroe and sections of surrounding towns. Targeted areas in Lafayette County include sections in the towns of Belmont and Fayette.
Residents in the affected areas can expect loud, low-flying, small, yellow planes as early as 5 a.m.
Stephanie Jentz, DATCP’s gypsy moth public information officer, did not yet have specific dates for the spraying locally.
“We usually start in the south because it’s a little warmer down here,” she said. Clear, calm weather conditions and adequate tree canopy development are factors in the decision of when and where to spray. The spraying is expected to end in the northern part of the state in July.
The predetermined target areas for spraying are based on data from a trapping program that catches male moths.
“We place about 11,000 traps,” Jentz said. “We can find where little hotspots or pockets of the insects are and then we target those areas.”
Planes fly low just above treetops so the treatment reaches the canopy leaves where gypsy moth caterpillars feast.
From mid-May to early June, planes will spray a treatment called Bacillus thuringiensis var. kurstaki (Btk) to kill caterpillars. Btk is made from a naturally-occurring soil bacteria and is used in certified organic food production. It is not toxic to people, bees, pets or other animals, however, the DATCP suggests people with severe allergies may prefer to stay indoors during nearby treatment applications.
In late June to early July, planes will spray a gypsy moth pheromone that prevents the adult male gypsy moths from finding the flightless females to reproduce.
When the pheromone blankets an area, “the males get confused,” Jentz said. Since female gypsy moths can’t fly, mating is disrupted.
In Monroe, Btk spraying is planned only in 220 acres around Honey Creek Park. The pheromone spraying is planned across a nearly 4,900-acre block that includes the entire city and surrounding land.
According to Christopher Foelker, DATCP’s gypsy moth program manager, aerial spraying “is the most efficient and effective treatment method to help slow the spread and delay the impacts associated with gypsy moth outbreaks.”
“It’s important to slow this invasive pest. Well-established gypsy moth populations cause damage to forests which impacts natural resources, wildlife, tourism and the timber industry,” he said in a statement.
The gypsy moth is a non-native pest that feasts on hundreds of species of trees and shrubs. Its preferred food source is oak leaves. Large populations can strip plants bare, leaving them vulnerable to secondary insect and disease attacks, even tree death. Gypsy moths are considered one of the most destructive invasive species worldwide.
To find more information on DATCP’s spraying program, including the latest spraying dates, search “gypsy moth” on the agency website, datcp.wi.gov, or call 800-642-MOTH (6684).