By Blake Jackson
The Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) will conduct aerial treatments for spongy moth (Lymantria dispar) in select areas of Buffalo, Grant, and Pepin counties starting in May.
This initiative is part of the national Slow the Spread of the Spongy Moth program. Residents in these western Wisconsin counties may notice loud, low-flying aircraft in the early mornings.
Spongy moth caterpillars are known to defoliate various trees and shrubs, causing stress and potential death to plants. This invasive pest can lead to financial burdens through the removal of dead trees and reduced property values.
Additionally, the bristly skins shed by the caterpillars can irritate human eyes, skin, and the respiratory system.
“Spongy moth spreads easily through movement of egg masses and larvae on firewood, vehicles, and outdoor objects, especially during population outbreaks like those we’ve seen across central and eastern Wisconsin over the last couple of years,” said Michael Falk, Forest Pest Survey and Control Unit Supervisor at DATCP. “Our 2025 treatment plan aims to prevent newly established populations from gaining a foothold in uninfested regions of western Wisconsin and to reduce future negative impact to our timber, nursery, and tourism industries.”
During May and early June, small yellow planes will spray Bacillus thuringiensis var. kurstaki (Btk) over treetops in targeted areas. This natural soil bacteria effectively kills spongy moth caterpillars that consume treated foliage.
Btk is an organic substance that breaks down quickly and is harmless to people, bees, pets, and other animals. Individuals with severe allergies might consider staying indoors during nearby spraying.
Treatment timing is contingent on spongy moth development and favorable weather, making precise dates difficult to predict in advance. On treatment days, spraying will commence as early as sunrise, with planes flying just above the trees in the treatment zones.
The national Slow the Spread program has significantly reduced the rate of spongy moth expansion. While Btk treatments are vital, federal funding uncertainties have led to a reduction in DATCP's treatment acreage for 2025. DATCP will also focus on other spongy moth control methods based on available federal funding.
For updates, residents can sign up for email notifications, call the Spongy Moth Hotline at (800) 642-MOTH, or email spongymoth@wisconsin.gov.
Photo Credit: moth-asian-gypsy
Categories: Wisconsin, General, Government & Policy