The warm temperatures have triggered the spongy moth caterpillars to emerge from their egg masses. Right now, the caterpillars are pretty tiny (see image below, taken 5/7), but you will likely see them as you are also starting to enjoy spring outdoors. These little caterpillars are going to keep feeding and growing to become large caterpillars that can do damage to our landscape trees. Once they get larger, you’ll recognize them by their distinctive red and blue dots on their backs and long hairs.

You have different options for managing spongy moths at different stages in their life cycle. Here are a variety of resources for you to check out to help you deal with spongy moths in your yard:

First, check out the recent article from our UW-Madison entomologist, PJ Liesch about spongy moth season: https://insectlab.russell.wisc.edu/2023/05/05/2023-spongy-moth-season-kicks-off-in-wisconsin/

You can learn more about spongy moths and what you can do at the following website: https://go.wisc.edu/kz1yc1 or check out this video recording of Spongy Moths: What to Expect in 2023, presented by Mike Hillstrom, Forest Health Specialist from the Wisconsin Department of Natural Resources (DNR) and PJ Liesch, Entomologist and Director of the University of Wisconsin Insect Diagnostic Lab: https://youtu.be/E1–rd47ess

Spongy moth caterpillars emerged, 5/7/2023