Hemlock Woolly Adelgid

The hemlock woolly adelgid (HWA) is an invasive, aphid-like insect native to Japan. It was first reported in the U.S. in Virginia in 1951. Since its introduction, HWA has spread to 19 states from Georgia to southern Maine, threatening the range of eastern hemlock (Tsuga canadensis). In New England, the insect feeds on and kills all sizes and age classes of hemlock usually within 5-10 years. Millions of trees have been infested or killed across the eastern U.S.

Ecologist Dave Orwig oversees HWA research at the Harvard Forest and across southern New England.