What to do about increase in gypsy moths

stages of Gypsy moth
There are actions you can take at various stages of the gypsy moth’s life cycle. At left are the egg masses. At center is a caterpillar, which can grow to about 2 inches in length. Caterpillars have five pairs of raised blue spots followed by six pairs of raised red spots along their backs. At right are adults. The female is larger and white while the male is smaller and brown. From left, photos are courtesy Milan Zubrik, Forest Research Institute – Slovakia, Bugwood.org; Jon Yuschock, Bugwood.org, and USDA APHIS PPQ , USDA APHIS PPQ, Bugwood.org

This spring, the New York State Department of Environmental Conservation (DEC) received reports of larger-than-usual gypsy moth populations and leaf damage on trees in the state. Cornell Cooperative Extension in Niagara County found that last year as well.

Gypsy moths are non-native but are naturalized, meaning they will always be around. Their populations spike in numbers roughly every 10 to 15 years, but these outbreaks are usually ended by natural causes such as disease and predators. Because of this, DEC and its partners typically don’t manage it. At this time, DEC doesn’t provide funding for treating gypsy moths on private property. 

The caterpillars you are seeing now will begin to disappear around mid-July when they pupate and become moths, according to the DEC. Spraying insecticides is not effective at this late stage of caterpillar development. This time of year, you may choose to use or make a trap on your trees to catch caterpillars while they are still crawling, though this will not erase the population. Please monitor your traps regularly for unintended wildlife that may pass through.

In winter, you can help DEC predict next year’s population numbers by conducting egg sampling surveys.

In spring, you may scrape egg masses to prevent some hatching, though that will also not erase the population. The spikes in gypsy moth numbers are an unfortunate but cyclical part of New York’s forests. 

You can view DEC’s recent Facebook Live about gypsy moths and answers to common questions about them on the DEC’s Facebook page. See more information on gypsy moths on the DEC website.

2 Comments on “What to do about increase in gypsy moths

  1. When we had an outbreak of gypsy moths we used clear plastic wrap tightly around our trees and then sprayed any cocoon with Pine Sol (original). It was pretty effective.

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