Spongy Moth

The spongy moth is one of the most important forest pests in the Northeast. The caterpillars feed on leaves of the forest, shade, ornamental and fruit trees, and shrubs. A single defoliation can kill some evergreens, but usually, two or more defoliations are needed to kill hardwoods.

What To Do

JULY: “Crush & brush” pupae and adult females

Spongy moth ( Lymantria dispar) is immobile during its pupal stage and can be crushed or brushed into a container of soapy water to prevent them from making it to the adult stage. If caterpillars have been abundant in your area, do some thorough scouting to check for the brownish pupae (3/4 – 2 1/2 inches long), which are often tucked away in protected spots.

Adult spongy moths appear within two weeks. Adult females (pale colored) have limited mobility and can also be crushed or brushed into a container in soapy water. Since each female can easily lay upwards of 1,000 eggs, eliminating adult female moths could help prevent future problems!

Note: Adult female spongy moths possess a long-lasting chemical pheromone that strongly attracts male spongy moths. Getting this pheromone on your skin, clothing, or objects such as gardening tools can make contaminated surfaces attractive to male moths. Using a disposable item (stick, etc.) to crush adult females can be helpful in this regard.

Check out more management techniques to apply during the year at the University of Wisconsin-Madiison Spongy Moth Management page.

Resources

Cornell University Fact Sheet

Forest Health Fact Sheet

Spongy Moth Management Guide for Homeowners

Btk Pesticide Treatment Info

How to Care for Defoliated Trees

How to Properly Water Your Trees

Last updated July 7, 2023