The European gypsy moth (Lymantria dispar dispar) is an invasive forest pest that feeds on more than 300 species of deciduous trees and shrubs, including aspen, oak, and birch. Repeated removal of leaves, or defoliation, stresses trees and can leave them vulnerable to disease or other pest infestations that can kill trees. Once they become established in a location, gypsy moth has cycles of large population outbreaks every eight to 12 years, leading to widespread defoliation and nuisance from caterpillars.
Gypsy moth egg masses are well-camouflaged and easily transported on firewood and other items such as camping equipment stored outdoors during the summer.
Gypsy moth has expanded from its initial introduction in Massachusetts south to Virginia, north to the Canadian Maritime Provinces, and west to the eastern edge of Minnesota. In Minnesota, gypsy moth is found most frequently in the southeast and northeast corners of the state because the invasion front is moving in from the east.
The Minnesota Department of Agriculture Gypsy Moth Program has conducted annual detection trapping surveys for gypsy moth since 1973. They have successfully eradicated all small, isolated infestations that have been found throughout the state eradication area. They have also conducted dozens of successful mating disruption treatments along the eastern border of the state over the years to slow the spread of gypsy moth.