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Hemlock Woolly Adelgid

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Hemlock Woolly Adelgid
Hemlock Woolly Adelgid, Adult with wax removed - Michael Montgomery USDA, Forest Service
Scientific Name: 
Adelges tsugae (Annand) (Annand 1928)
Common Name: 
Hemlock Woolly Adelgid (HWA)
Native To: 
Date of U.S. Introduction: 
Discovered on the West Coast in the 1920s, but it is disputed whether this was an introduced or native population; an introduced population was discovered on the East Coast in the 1950s (Havill et al. 2006; Orwig et al. 2003)
Means of Introduction: 
Destroys Eastern hemlock trees (Tsuga canadensis) (Orwig et al. 2003)


  • USDA. FS. Southern Research Station. CompassLive.

    Laricobius nigrinus is a small beetle that eats an even smaller bug – the hemlock woolly adelgid, or HWA. Since 2003, Laricobius has been used to help control HWA. But the beetle, which is native to western North America, is only active during the fall, winter and early spring. Recently, USDA Forest Service research entomologist Bud Mayfield and his colleagues, including students and prominent researchers, published the results of a six-year collaboration on Laricobius as biocontrol.

    Silvicultural recommendations for managing HWA are still in development. But when they are available, Mayfield and his colleagues plan to update their resource manager’s guide. They wrote the guide for managers who want to use an integrated pest management strategy to control hemlock woolly adelgids.

Distribution / Maps / Survey Status




Selected Resources

The section below contains highly relevant resources for this species, organized by source. Or, to display all related content view all resources for Hemlock Woolly Adelgid.


USDA. Forest Service; Southern Regional Extension Forestry. Forest Health Program.

See also: Hemlock Woolly Adelgid for more resources

National Plant Diagnostic Network.

You can become a more effective First Detector by familiarizing yourself with invasive target pests and pathogens known to exist in the U.S. If you think you have encountered one of the species or disease complexes listed, report its presence.

Nature Conservancy. Don't Move Firewood.
IUCN. Species Survival Commission. Invasive Species Specialist Group.

New York Invasive Species Clearinghouse.

Texas State University System. Texas Invasive Species Institute.
Federal Government
State and Local Government

Wisconsin Department of Natural Resources.

Maryland Department of Agriculture.

Pennsylvania Department of Conservation and Natural Resources.

Maine Department of Conservation. Maine Forest Service. Forest Health and Monitoring Division.

Ohio Department of Agriculture. Plant Health.

New York Department of Environmental Conservation.
University of Maryland. Cooperative Extension. Home and Garden Information Center.

Rutgers University. New Jersey Agricultural Experiment Station.

University of Minnesota.
IPM of Midwest Landscapes is available for educating growers, landscapers, managers, and consumers in the principles of IPM and its application to managing the over 150 common insect species in Midwest landscapes.
Cornell University. Cooperative Extension of Suffolk County. Horticulture Diagnostic Laboratory.
See also: Tree and Shrub Insect Pests for more fact sheets.
Columbia University. Center for Environmental Research and Conservation.
Pennsylvania State University. Cooperative Extension.

Cornell University. Forest Health and Invasive Non-native Forest Pests.