Spongy moth (Lymantria dispar) was brought to North America in 1869 by an artist named Mr. L. Trouvelot in a misguided attempt to breed a hardy silkworm. Some escaped and the first recorded defoliation by spongy moth was in 1889 of the street trees in Trouvelot’s own neighborhood of Medford, Massachusetts.

Lacking many natural enemies, spongy moth has escalated into one of the most important insect pests of forest and shade trees in the eastern United States. They have moved steadily westward ever since, reaching Wisconsin in the late 1980s.

Spongy moth is native to Europe, Asia, and North Africa. It has succeeded so well in North America for several reasons:

• This species is very hardy. In its native range, the spongy moth can be found from the frigid Russian steppes to the subtropical shores of the Mediterranean.
• Spongy moth is not fussy about what it eats; it has been recorded feeding on over 300 species of trees and shrubs.
• Finally, when spongy moth was introduced into North America, none of the natural enemies that attacked it in its native range were present. Pest managers have since introduced some of the parasites and diseases that suppress spongy moth populations in Europe and Asia, but only about a dozen are well established in North America.