BugwoodWiki Article

hemlock woolly adelgid
Adelges tsugae Annand, 1924

Overview

Origin
Hemlock woolly adelgid, Adelges tsugae, is an invasive insect in eastern North America. DNA evidence suggests that the invasive eastern U.S. population came from Japan and not the western United States, where the species feeds on western hemlock (Tsuga heterophylla [Raf.] Sarg.) but is believed to be native and is not a pest.
Life Cycle
Hemlock woolly adelgids are small in size and to the naked eye only their woolly coverings are easily visible. The insect has two generations per year and growth occurs from fall through late spring. Insects in summer are inactive and scarcely visible at the bases of needles as black dots. Woolly masses (the sign allowing the species to be recognized) develop in October and are present thereafter through June of the following year.
Distribution
In the eastern USA, Adelges tsugae is killing eastern hemlocks (Tsuga canadensis [L.] Carrière) and Carolina (Tsuga caroliniana Engelm.) in large numbers from Connecticut south along the Appalachian Mountains. From Massachusetts north, or at high elevations, tree mortality has been restrained by higher rates of mortality of adelgids in winter due to low temperatures.
Control Efforts
A biological control program is in progress against this pest, based on specialized predatory beetles that feed only on adelgids, collected in western North America (Laricobius nigrinus Fender) or China/Japan (species of Laricobius and various Scymnus ladybird beetles). To date, releases have not demonstrated any reductions in adelgid densities from predators. Populations of L. nigrinus have become well established and abundant in some areas of western North Carolina.

Resources

Selected Images


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2167011

hemlock woolly adelgid
Adelges tsugae
Infestation
William M. Ciesla
3225076
3225076

hemlock woolly adelgid
Adelges tsugae
Biological Control
Dennis J. Souto
3225077
3225077

hemlock woolly adelgid
Adelges tsugae
Adult(s)
Connecticut Agricultural Experiment Station Archive
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5018075

hemlock woolly adelgid
Adelges tsugae
Infestation
Pennsylvania Department of Conservation and Natural Resources - Forestry Archive
1748045
1748045

hemlock woolly adelgid
Adelges tsugae
Infestation
Robert L. Anderson
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1748048

hemlock woolly adelgid
Adelges tsugae
Infestation
Robert L. Anderson
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1344014

hemlock woolly adelgid
Adelges tsugae
Control
Great Smoky Mountains National Park Resource Management Archive
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1276003

hemlock woolly adelgid
Adelges tsugae
Adult(s)
Michael Montgomery

Taxonomic Rank

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Atelocerata
Class: Hexapoda (including Insecta)
Infraclass: Neoptera
Subclass: Pterygota
Order: Hemiptera
Suborder: Sternorrhyncha
Superfamily: Aphidoidea
Family: Adelgidae
Subfamily: Adelginae
Tribe: Adelgini
Genus: Adelges

Other System Links

NPDN Pest: IRAZAHA

References

Common Name Reference: Bosik, J. J. Common Names of Insects and Related Organisms 1997. Lanham, MD: Entomological Society of America (ESA), 1997. 232 pp.

Scientific Name Reference: R.W. Poole and P. Gentili, Nomina Insecta Nearctica. 1996. Nomina insecta nearctica: a checklist of the insects of North America. Vol. 4. Rockville (MD): Entomological Information Services. Available at URL: http://www.nearctica.com/nomina/main.htm