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DNR urges landowners to survey for Gyspy Moth egg masses

Populations could rise in 2021, due to high numbers of egg-laying female moths

MADISON, Wis. -- In response to an increase in Gypsy Moth populations, it is important to start removing egg masses to prepare for the spring, according to Wisconsin state agencies.

Earlier this year during May and June, The Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) conducted annual aerial spraying to help control Gypsy Moth populations in 18 counties across Wisconsin.

However, according to the Department of Natural Resources, populations could rise in 2021, due to high numbers of egg-laying female moths.

An invasive pest from Europe, Gypsy Moth caterpillars can cause severe defoliation on the leaves of many species of trees and shrubs.

From now until spring, landowners can help reduce next year’s caterpillar population by treating or removing egg masses. Gypsy moth egg masses are tan, tear-dropped, and about the size of a quarter. Each egg can hold 600 to 1,000 eggs.

According to the DNR, only egg masses produced during the past summer will have viable eggs to kill. Viable egg masses will be firm and exhibit a dark tan color. Older egg masses will be spongy to the touch and look faded.

The masses can be found on trees, buildings, fences, firewood piles, or any outdoor item. When found, the egg masses can be removed or treated safely by either directly spraying horticultural oil or gently scraping the entire egg mass into a container of warm soapy water. After soaking the egg for a few days, discard the egg in the trash.

Severe winter temperatures and snow cover are also beneficial in killing gypsy moth eggs to decrease the number of caterpillars hatched in the following spring. However, populations can quickly rebound when given the right environmental conditions.

The WI DNR urges landowners to survey for Gypsy Moth egg masses in order to predict next summer’s moth populations.

If you live in a non-quarantined county, you can report such issue by calling (608) 642-MOTH or email ing Please provide a name, phone number and address of your property including township, village or city. ​If you live in a quarantined county, you can also learn more about managing gypsy moth on yard trees and in your woodlot at​.

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