European Gypsy Moth



Lymantria dispar


Gypsy moths’ characteristics make them easily distinguishable from other leaf-feeding caterpillars. They are dark in color and covered with hair. Their backs are lined with five pairs of blue dots and six pairs of red dots. In caterpillar form, they can grow to approximately 38 to 50 mm in length.


The European gypsy moth was discovered in the United States in 1869 in Massachusetts. It spread throughout the northeast and has become one of the country’s most destructive hardwood forest pests. It is known to defoliate acres of forest and urban trees. The defoliation alters forest composition and destroys the habitats of many birds and mammals. It is native to Europe, southern Asia and northern Africa. In the United States, it most commonly is found in Pennsylvania, New Jersey, New York and Delaware.

European gypsy moths feed on a wide variety of plants. Young larvae tend to feed primarily on oaks, birch, willows and alder. Older larvae prefer cedar, pine, spruce and fir.


The females are known to lay between 500 and 1,000 eggs. They typically lay their eggs underneath tree bark or in shaded areas. Eggs are covered with a mass of tan-colored hairs that is around 38 mm in length and 19 mm in width. Gypsy moths overwinter in their egg stage. Eggs attach to many outdoor objects, including trees and houses. The eggs hatch into caterpillars during the larva stage.


The European gypsy moths are voracious eaters, defoliating millions of trees annually. Some common signs of a gypsy moth infestation are the defoliation of trees, holes in leaves and egg masses on tree trunks or any outdoor furniture.


There are ways to manage a gypsy moth infestation. If the population is small, the egg masses can be destroyed by burning or crushing the eggs or placing them in a bucket of soapy water. Simply picking them off their nesting place, however, often can yield the same effect. Be careful when handling egg masses, because the hairs that cover them could cause an allergic reaction.

Wrapping burlap around tree trunks provides a hiding place for larvae and makes monitoring their population easy. Barrier bands can keep larvae from crawling up tree trunks. Large populations require more extensive treatment. Several insecticides have been used successfully in managing gypsy moth populations.

To reduce the chance of an infestation, make sure to water trees during a drought and increase soil moisture by placing mulch around the base of trees. For more information or assistance, consult with your local extension service.