Hemlock Woolly Adelgid

INTRODUCTION: The Hemlock Woolly Adelgid (HWA) is a tiny, aphidlike insect native to Asia, believed to have accidentally entered North America on imported nursery plants. It is now a serious pest of eastern hemlock (Tsuga canadensis) in the U.S. HWA were first reported on the west coast in the 1920’s, then near Richmond, VA, around 1950. Although west coast species of hemlocks appear resistant to HWA, eastern species have been ravaged by this pest. The potential ecological impacts of this pest are extensive. Eastern hemlock stands provide critical shelter and a unique habitat for many birds and wildlife, and are important in maintaining forest stream ecosystems. There is not an ecologically equivalent tree species that can take the place of eastern hemlock.