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Gypsy Moths (Lymantria dispar) are an invasive species from Eurasia. They were introduced into the U.S.A in 1869 and have become a serious pest of deciduous trees.

Gypsy moths overwinter in egg masses as shown in the photograph above, each containing perhaps several hundred eggs. The eggs hatch into caterpillars which feed on the leaves of nearby trees. After the caterpillars have reached full size they form pupa and in about 2 weeks the adult moths emerge. The caterpillars are the only life stage that is destructive. If the numbers of caterpillars are large and if they persist in the same area for several years the trees can be severely stressed or even killed. They feed on many species of trees, but appear to prefer oaks.

One effective means to control Gypsy Moths is to find the egg masses during the fall and winter and destroy them. Perhaps the easiest method is to spray the egg masses with a safe oil. Contact your local extension office for instructions and assistance.


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Last updated on June 11, 2014