New Spongy Moth Reporting Tool

Dane County now has a powerful tool to create an initial, large-scale inventory of pest locations and outbreaks. The new Spongy Moth Outbreak Map allows us to see the distribution of spongy moth outbreaks across the region and enables anyone to add new locations with a simple click. Many thanks to Matt Krempely, CARPC’s Planning Intern and UW master’s student in Urban & Regional Planning, for developing this tool.

The spongy moth (formerly known as “gypsy moth”) are an invasive species known to completely strip infested trees and shrubs of their leaves, potentially killing them. Wisconsin is currently experiencing a spongy moth outbreak. Such outbreaks typically occur every 10 to 15 years and are exacerbated by the ongoing drought conditions.

At the moment, we know relatively little about the geography and extent of the current outbreak in Dane County. Initial reporting in Madison indicates widespread outbreaks with localized, significant outbreaks clustered on the west side, including private properties, parks, greenways, street trees, the UW-Lakeshore Nature Preserve, and possibly the UW-Madison Arboretum.

This distribution bears a historical resemblance to the 2008-2011 outbreak recorded during the city, county, and state suppression program. During that period in Madison, site-scaled tree inventories were created and updated with apparently annual aerial suppression sprays. In Madison, suppression efforts covered 12 spray blocks in 2008, 35 blocks (1,862 acres) in 2010, and 12 blocks in 2011. Sites across the county were also included in this program.

Statewide, spongy moths have defoliated over 370,000 acres this year as reported by the Wisconsin DNR. Fortunately, there are actions municipalities and landowners can take to mitigate the impacts of the outbreak, which is not always the case for other tree pests and diseases.

To help combat this outbreak, pay closer attention to the oaks you come across as you are out and about this fall. Bur oaks particularly, with their deeply crevassed bark, seem to be the perfect place for invasive spongy moths to lay their egg masses. Other preferred species include birch, crabapple, aspen, and willow.

If you see egg masses in the furrows of the bark branches, that means there is potential for defoliation and mortality issues in this area next year. Report it on the new  2023 Spongy Moth Outbreak Map to help our communities know what to expect and take proactive action.

Municipal parks and forestry staff, along with community leaders, are invited to attend a spongy moth information meeting and field tour organized by Brian Wahl (WDNR) coming up on Tuesday, September 19^th from 9 to 11AM in the Fitchburg Library “Meeting Room” and Greenfield Park.