Help Remove Gypsy Moth Egg Masses: DNR To WI Residents

WISCONSIN — The Wisconsin Department of Natural Resources is asking residents to help remove gypsy moth egg clusters this fall.

The Wisconsin Department of Agriculture, Trade and Consumer Protection caught more than 83,000 moths in 2020, Wisconsin Public Radio reported. The moth can damage trees and shrubs by eating their leaves.

The moths leave tan-colored, lumpy egg masses about the size of a nickel or quarter, the wildlife agency said. Each mass holds hundreds of egg and can be found on trees and buildings and in other places such as firewood piles and birdhouses.

The following are areas where moth populations grow the fastest and are primarily found.

• Tree species such as oak, crab apple and birch that grow on mowed lawns.
• Large oaks with rough bark that are on or adjacent to mowed lawns.
• Dry sites with sandy soil and abundant oak.

Spotting egg masses can help residents predict how many moths will hatch the following summer, the agency said. Residents can see egg masses more easily after leaves have fallen from trees.

Treating or removing egg masses in the fall keeps them from hatching into hungry caterpillars in the spring, the agency said. Many caterpillars can kill trees because of their voracious activity.

Residents should spray egg masses with horticultural oil or gently scrape them into a container full of soapy water, then soak them for a few days before discarding them, the agency said. Don't use motor oil or other lubricants as these can harm a tree.

Old masses with dead eggs will be faded and feel spongy, the agency said.

Dry weather will let more caterpillars hatch in southern Wisconsin counties in 2022, the agency said. Southern counties were driest in the past spring and summer.