northeast WI Forest health

DNR Urges Spring Spongy Moth Treatment Plans

Posted on by akabelowsky
Carefully scraping spongy moth egg masses off trees and into a cup of soapy water will help to hold down caterpillar damage in 2025.

Carefully scraping spongy moth egg masses off trees and into a cup of soapy water will help to hold down caterpillar damage in 2025. / Photo Credit: Bill McNee, Wisconsin DNR

By Bill McNee, DNR Forest Health Specialist
Bill.McNee@wisconsin.gov or 920-360-0942

The Wisconsin Department of Natural Resources (DNR) encourages property owners to examine their trees for spongy moth egg masses and determine whether control measures are needed this spring.

Property owners who have oak, birch, crabapple, aspen, willow and linden (basswood) trees should be particularly watchful because the caterpillars of this invasive insect prefer these species. However, they will feed on many other kinds of trees and shrubs.

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Spongy Moth Status Update

Posted on by akabelowsky

By Bill McNee, DNR Forest Health Specialist, Oshkosh;
Bill.McNee@wisconsin.gov or 920-360-0942

A photo showing several trees with spongy moth defoliation in Marinette County in mid-June 2024.

Spongy moth defoliation in Marinette County in mid-June 2024. / Photo Credit: Darrek Sams, Wisconsin DNR

As of early July, we have seen a mix of live and dead caterpillars and tree defoliation that is typical of a late-stage spongy moth outbreak. Reports of defoliation have been received as far north as Florence County.

Recent aerial surveys in southern Wisconsin spotted defoliation in the same general areas as in 2023, but the defoliation has generally been less intense this year. Information for northern Wisconsin has yet to be made available. Refoliating oaks, growing a second set of pale-looking leaves, were seen in Walworth County in early July.

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