The gypsy moth, Lymantria dispar, is one of North America's most devastating forest pests. The species originally evolved in Europe and Asia and has existed there for thousands of years. In either 1868 or 1869, the gypsy moth was accidentally introduced near Boston, MA by E. Leopold Trouvelot. About 10 years after this introduction, the first outbreaks began in Trouvelot's neighborhood and in 1890 the State and Federal Government began their attempts to eradicate the gypsy moth. These attempts ultimately failed and since that time, the range of gypsy moth has continued to spread. Every year, isolated populations are discovered beyond the contiguous range of the gypsy moth but these populations are eradicated or they disappear without intervention. It is inevitable that gypsy moth will continue to expand its range in the future. Gypsy moth was first discovered in Pennsylvania near Pittston, in Luzerne and Lackawanna counties in 1932. During the 30's and 40's it continued to spread to Pike, Lackawanna, Wayne, Monroe, and Carbon counties. By 1969, it had spread west of the Susquehanna River, and by 1980, 38 Pennsylvania counties were infested. The gypsy moth has now moved beyond our state. It is now found as far west as Minnesota, with populations reaching outbreak levels every 5-10 years.