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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: Eastern U.S.; Western U.S. (not considered a pest)




Selected Resources:

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New York Invasive Species Information - Hemlock Wooly Adelgid
New York Invasive Species Clearinghouse.

Gallery of Pests - Hemlock Woolly Adelgid
Nature Conservancy. Don't Move Firewood.

TISI Inventory - Hemlock Woolly Adelgid
Texas State University System. Texas Invasive Species Institute.

Gallery of Forest Pests - Hemlock Woolly Adelgid
Vermont Invasives.

Invasive Species Compendium - Adelges tsugae
CAB International.

Global Invasive Species Database - Adelges tsugae (insect)
IUCN. Species Survival Commission. Invasive Species Specialist Group.

Federal Government

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

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

State Government

Fact Sheet: Hemlock Woolly Adelgid (PDF | 275 KB)
Connecticut Agricultural Experiment Station.
See also: Publications - All CAES Factsheets for more resources

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

Hemlock Woolly Adelgid
Maryland Department of Agriculture.

Michigan Invasive Species - Hemlock Woolly Adelgid
State of Michigan.

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.

Hemlock Woolly Adelgid
Wisconsin Department of Natural Resources.


Hemlock Woolly Adelgid (2006; PDF | 239 KB)
University of Maryland. Cooperative Extension. Home and Garden Information Center.
See also: Home and Garden Information Center Publications for more factsheets

The Hemlock Woolly Adelgid: Life Cycle, Monitoring, and Pest Management in New Jersey
Rutgers Cooperative Extension. New Jersey Agricultural Experiment Station.

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

New York State Hemlock Initiative (NYSHI)
Cornell University. Forest Health and Invasive Non-native Forest Pests.

Hemlock Woolly Adelgid (PDF | 437 KB)
Cornell University. Cooperative Extension of Suffolk County. Horticulture Diagnostic Laboratory.
See also: Tree and Shrub Insect Pests for more fact sheets.

IPM of Midwest Landscapes: Pests of Trees and Shrubs - Hemlock Wooly Adelgid (2004; PDF | 78 KB)
University of Minnesota.
IPM for 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.

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


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. Proceedings: Symposium on Sustainable Management of Hemlock Ecosystems in Eastern North America. GTR-NE-267: 104-109.

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Last Modified: Sep 03, 2018
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