The gypsy moth (Lymantria dispar) was brought to the U.S. in 1869 to experiment with silk production. Populations soon established and the pest has been expanding in distribution since. Adult females are not able to fly. Gypsy moth larvae spin a thread of silk and disperse in the wind. It is estimated that this natural spread would be about 2 miles per year. The actual rate of spread has been much greater due to human aid, primarily by movement of nursery stock and automobiles.