02/15/2025
Want to take action to protect your trees and property from hungry spongy moth caterpillars? Now is a great time to declare open season on spongy moth egg masses by examining your trees and scraping away those future caterpillars.
Spongy moth egg masses are tan-colored lumps about the size of a nickel or quarter. Each contains hundreds of eggs. They can be found on trees, buildings and other outdoor objects such as firewood piles and birdhouses.
Eggs begin to hatch from mid-April to early May, sending caterpillars out in search of leaves to devour. Egg masses are easier to find right now because most trees have no leaves.
Property owners have two options to remove egg masses as they are found:
1) Gently scrape them into a container of soapy water to soak for two days, then throw them into the trash;
2) Spray egg masses safely within reach with horticultural, mineral or neem oils approved for tree use. The oils will suffocate the tiny caterpillars inside the eggs.
Each egg mass removed means hundreds fewer caterpillars will emerge to cause trouble in the spring!
Learn more through Wisconsin's Spongy Moth Resource Center: https://spongymoth.wi.gov
