MADISON, Wis. – The Wisconsin Department of Natural Resources (DNR) has finalized aerial spraying plans for its 2025 Spongy Moth Suppression Program, with maps of the five selected treatment areas available online.
The treatment sites are at three state parks in Juneau, Marinette and Sauk counties. A total of 544 acres will be treated with an aerial spray of “Foray” bacterial insecticide containing Bacillus thuringiensis var. kurstaki. The treatments will be done to protect valuable trees in campgrounds and other recreational areas.
The specific sites and areas to be sprayed are:
- Juneau County: 85 acres in one block at Rocky Arbor State Park, including the campground.
- Marinette County: 252 acres in two blocks at Governor Thompson State Park, including the campground and Woods Lake day-use area.
- Sauk County: 207 acres in two blocks at Mirror Lake State Park, including the campgrounds.
The aerial spraying will occur between mid-May and early June, with exact dates and times dependent upon caterpillar development and weather conditions. The DNR intends to avoid spraying high-use properties during the extended Memorial Day weekend if spraying has not occurred by then.
Law enforcement, local governments, schools and nearby medical facilities will be notified before spraying.
For up-to-date information, visit the Wisconsin Spongy Moth Resource Center and subscribe to email updates that will provide notice when spraying dates are determined. Also, the toll-free Spongy Moth Hotline, 800-642-MOTH (800-642-6684), has a recording of up-to-date spraying plans.
The State of Wisconsin does not offer a state-sponsored or cost-share program for treating private property to prevent defoliation by spongy moth. Those interested in organizing a spray program at their own expense can view the DNR’s “Organizing An Aerial Spray For Forest Pests” guide. Landowners may also hire tree-care businesses to apply insecticide from the ground.
Learn more about spongy moth and management options in the Wisconsin Spongy Moth Resource Center.
