Since 1981, the gypsy moth has defoliated more than a million acres each year in the eastern U.S. Infestations alternate between years of little defoliation followed by periods of 2 to 4 years of heavier defoliation when gypsy moth populations are heavier. Gypsy moth caterpillars eat a wide variety of plant materials. They have been recorded to feed on over 500 tree, shrub, and vine species. Oak trees are the preferred food. Infestation and heaviest defoliation in Delaware have been along our western boundary with Maryland where oaks predominate in our woodlots.
Populations are now very high in Kent County and western Sussex County.
The gypsy moth is not a native insect. It was brought to the U.S. before laws governing importation of organisms were in force. It was considered a potential caterpillar for production of silk. An amateur French naturalist accidentally released gypsy moths from his home in Medford, Mass., in 1869. The first outbreak of the moth as a forest pest was 1889.