The Sconi

The Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) is set to commence aerial spraying in May as part of the national Slow the Spread of the Spongy Moth program. The initiative will target areas in three western Wisconsin counties, where residents may notice low-flying planes early in the morning.

Spongy moths, during their caterpillar stage, pose a threat by defoliating various trees and shrubs. This can lead to plant stress and even death, potentially affecting property values due to tree removal costs. Additionally, the caterpillars' bristly skins can cause irritation to human eyes, skin, and respiratory systems.

"Spongy moth spreads easily through movement of egg masses and larvae on firewood, vehicles, and outdoor objects," 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."

The treatment involves using small yellow airplanes to spray Bacillus thuringiensis var. kurstaki (Btk), a naturally occurring soil bacteria that targets spongy moth caterpillars without harming people or animals. While Btk biodegrades within days, individuals with severe allergies are advised to remain indoors during treatments.

Spraying schedules depend on weather conditions and moth development stages; thus exact dates cannot be predetermined. Planes will operate from sunrise until completion or as long as conditions allow.

Despite an 87% reduction in spongy moth spread rates over two decades due to this national program, financial constraints have led DATCP to scale back Btk treatment areas from five counties to three for 2025. Additional control activities will be prioritized based on federal funding availability.

For updates on treatment plans or inquiries, residents can sign up for notifications or contact DATCP through their hotline or email.