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You are here: Home / Animals / Species Profiles / Hemlock Woolly Adelgid
Species Profiles

Hemlock Woolly Adelgid

Hemlock Woolly AdelgidScientific name: Adelges tsugae (Annand) (Annand 1928)

Common name: Hemlock Woolly Adelgid

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Selected Resources

Native To: Japan (Orwig et al. 2003)

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: Accidental (Wallace and Hain 2006)

Impact: Destroys Eastern hemlock trees (Tsuga canadensis) (Orwig et al. 2003)

Current U.S. Distribution:




Selected Resources:

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Invasive Species Compendium - Adelges tsugae
CAB International.

Hemlock Woolly Adelgid
Vermont Invasives.

Hemlock Woolly Adelgid
Nature Conservancy. Don't Move Firewood.

Global Invasive Species Database - Adelges tsugae (insect)
World Conservation Union. Invasive Species Specialist Group.


Forest Disturbance Processes - Hemlock Woolly Adelgid
USDA. FS. Northern Research Station.

Pest Alert: Hemlock Woolly Adelgid
USDA. FS. Northeastern Area.

Hemlock Woolly Adelgid
USDA. FS. Northeastern Area. State and Private Forestry.
Note: Distribution Maps and HWA Working Group Coordinating Committee

Hemlock Woolly Adelgid
DOI. NPS. Great Smoky Mountains National Park.


Hemlock Woolly Adelgid
Connecticut Agricultural Experiment Station.

Hemlock Woolly Adelgid In Maine
Maine Department of Conservation. Maine Forest Service. Forest Health and Monitoring Division.

Hemlock Woolly Adelgid
Maryland Department of Agriculture.

Hemlock Woolly Adelgid
Michigan Department of Agriculture and Rural Development.

Hemlock Woolly Adelgid
New York Department of Environmental Conservation.

Hemlock Woolly Adelgid
Ohio Department of Agriculture. Plant Health.

Hemlock Woolly Adelgid
Pennsylvania Department of Conservation and Natural Resources. Forestry.

Hemlock Woolly Adelgid
Wisconsin Department of Natural Resources.


Hemlock Woolly Adelgid (HG2)
University of Maryland. Cooperative Extension. Home and Garden.

The Hemlock Woolly Adelgid: Life Cycle, Monitoring, and Pest Management in New Jersey (PDF | 193 KB)
Rutgers Cooperative Extension. New Jersey Agricultural Experiment Station.

Introduced Species Summary Project - Hemlock Woolly Adelgid
Columbia University. Center for Environmental Research and Conservation.

Hemlock Woolly Adelgid (PDF | 437 KB)
Cornell University. Cooperative Extension of Suffolk County. Horticulture Diagnostic Laboratory.

Invasive Plants and Insects: Hemlock Woolly Adelgid
Pennsylvania State University. Cooperative Extension.

Hemlock Woolly Adelgid
Texas State University System. Institute for the Study of Invasive Species.




Annand, N.P. 1928. A contribution toward a monograph of the Adelginae (Phylloxeridae) of North America. Stanford, Calif.: Stanford University Press.

Havill, N.P., M.E. Montgomery, G. Yu, S. Shiyake, and A. Caccone. 2006. Mitochondrial DNA from hemlock woolly adelgid (Hemiptera: Adelgidae) suggests cryptic speciation and pinpoints the source of the introduction to eastern North America. Annals of the Entomological Society of America 99(2):195-203.

Orwig, D.A., D.R. Foster, and D.L. Mausel. 2003. Landscape patterns of hemlock decline in New England due to the introduced hemlock woolly adelgid. Journal of Biogeography 29(10-11):1475-1487.

Wallace, M.S., and F.P. Hain. 2000. Field surveys and evaluation of native and established predators of the hemlock woolly adelgid (Homoptera: Adelgidae) in the southeastern United States. Environmental Entomology 29(3):638-644.

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Last Modified: Nov 18, 2015
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