hemlock woolly adelgid
Adelges tsugae Annand, 1924

Hemlock woolly adelgid (HWA) is native to Japan and possibly China. It was first observed in western North America in the early 1920's and had moved east to Virginia by the 1950's. In the eastern United States, HWA is now found from northern Georgia, north along the Appalachian Mountains to southern New England. Movement of live infested hemlocks, wind, birds, and mammals disperse it on a local scale. Hosts include forest and ornamental hemlock trees (Tsuga spp.). HWA is a serious pest of eastern hemlock and Carolina hemlock. Size varies from 1/16 to 1/8 of an inch in length with piercing/ sucking mouthparts. All adults are female with each female producing 50-300 eggs in a lifetime. It produces increasing amounts of white, woolly wax used to protect itself and its eggs. A sign of infestation is the presence of what appears to be the tips of cotton swabs on the bases of needles. Needle loss and twig desiccation, caused by the insects feeding, hinders shoot growth. Needle loss is followed by twig die-back, defoliation, and death, usually within four to six years of infestation. Severe infestations can eliminate the hemlock component from forest stands.

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