The gypsy moth is one of the most destructive forest pests in
the Eastern and North Central United States. It was introduced
in 1869 and has been detected and/or established in all 7 of the
states in the North Central Region, and continues to spread at
a rate of 13 miles per year in areas without a comprehensive intervention
strategy. Larvae prefer hardwoods, but may feed on hundreds of
species of trees and shrubs, including pines, cedars, hemlocks,
and spruce. The moth prefers oaks, apple, sweetgum, speckled alder,
basswood, gray and white birch, poplar, willow, and hawthorne,
although other species are known to be affected, and the list
of suitable hosts will undoubtedly expand as the insect spreads.
The effects of defoliation range from reduced growth and die back
of twigs and branches, to mortality, depending on tree vigor,
as well as the severity and frequency of defoliation events. Hardwood
species are more resilient than softwoods; pines and hemlocks
subject to heavy defoliation are likely to die after a single
defoliation event of greater than 50 percent.
To learn more, see Forest
Service Forest Insect and Disease Leaflet 162. To view maps
and animations depicting changes in the presence and establishment
of the gypsy moth, choose either Flash
format or continuous animation.