The Wisconsin Department of Natural Resources is asking the public for help this fall by looking for and disposing of egg masses produced by adult gypsy moths during the summer. Gypsy moths are invasive pests that lay egg masses that are tan-colored lumps about the size of a nickel or quarter. Each mass contains hundreds of eggs and can be found on trees, buildings and other outdoor objects, including the inside of firewood piles and birdhouses.
In 2021, gypsy moth populations increased for a second consecutive summer due to weather conditions that allowed more caterpillars to survive and become adult moths.
Populations usually grow fastest and are often first noticed on preferred tree species, such as oak, crabapple and birch. Checking for egg masses helps residents predict the number of caterpillars for the following summer and take necessary action. You can discover more egg masses once leaves have fallen from the trees.
Treating or removing masses in the fall prevents large numbers of eggs from hatching into hungry, leaf-eating caterpillars in the spring. Large numbers of these caterpillars can be a tremendous nuisance that could even kill trees.
To treat or remove egg masses, spray the masses that are safely within reach with horticultural oil or gently scrape them into a container of soapy water to soak for a few days before throwing in the trash. Do not use motor oil or other lubricants, as these can harm the tree and be a pollutant. Old masses with no viable eggs will appear faded and feel spongy when touched.
Categories: Wisconsin, Rural Lifestyle