The gypsy moth (Lymantria dispar) was introduced in 1868 into the United States by Étienne Léopold Trouvelot, a French scientist living in Medford, Massachusetts. Because native silk-spinning caterpillars were susceptible to disease, Trouvelot imported the species in order to breed a more resistant hybrid species. Some of the moths escaped, found suitable habitat, and began breeding. The gypsy moth is now a major pest of hardwood trees in the Eastern United States.