The gypsy moth was brought to North America in 1869 in a misguided attempt to breed a hardy silkworm. Some escaped and the first recorded defoliation by gypsy moth was in 1889 of the street trees in Medford, Massachusetts.
Lacking many natural enemies, the gypsy moth has escalated into the most important insect pest of forest and shade trees in the eastern United States. They have moved steadily westward ever since, reaching Wisconsin in the late 1980s.
When the gypsy moth was introduced into North America, none of the natural enemies that preyed upon it in its native range were present. Pest managers have since introduced some of the parasites and diseases that suppress gypsy moth populations in Europe and Asia, but only about a dozen are well established in North America.
For more information on Gypsy Moth, click here.