gypsy moth, common name for a moth, Lymantria dispar, of the tussock moth family, native to Europe and Asia. Its caterpillars, or larvae, defoliate deciduous and evergreen trees and shrubs. Introduced from Europe into Massachusetts c.1869, the European gypsy moth became a serious pest within 20 years. Asian gypsy moths were introduced to the Northwest by Russian ships in 1991 and to North Carolina by a ship returning from Germany in 1993.
Adult gypsy moths have hairy bodies. Females, with a wingspread of about 2 in. (5 cm), or 3.5 in. (8.9 cm) in the Asian variety, are white with dark lines on the wings; the smaller males are gray. The female covers the egg mass with body hair and scales. The larvae emerge in the spring; their blackish bodies have yellow stripes and rows of blue or red tubercles bearing tufts of hair. When full grown they are about 2 in. long. Pupation (see insect) lasts about two weeks, and the adults emerge from the cocoon in midsummer.
European gypsy moth females do not fly; dispersal occurs chiefly in the egg and larval stages as the caterpillars are blown by the wind or transported on vehicles. Females of the Asian variety and hybrids do fly. In North America the European gypsy moth has spread through the NE United States and adjacent parts of Canada, west to Wisconsin and south to North Carolina. The Asian variety has begun to damage areas of the Pacific Northwest. Gypsy moths defoliate millions of acres of trees in the United States yearly; repeated infestations weaken and kill the trees. A variety of measures have been used to check their spread, including the implementation of stringent quarantine measures and aerial application of pesticides such as Bacillus thuringiensis and diflubenzuron (Dimilin).
The gypsy moth is classified in the phylum Arthropoda, class Insecta, order Lepidoptera, family Liparidae.