Hemlock Woolly Adelgid

The hemlock woolly adelgid (HWA), Adelges tsugae, is a non-native insect that feeds on sap and stored nutrients of eastern hemlock trees. This species, originally from Asia, has infested  hemlocks in the eastern United States since its accidental introduction in the 1950s. The insects are small and settle at the base of hemlock needles where they insert piercing, sucking mouthparts to feed. They cover themselves with a white, waxy secretion giving them the characteristic “cotton ball” appearance on the underside of the needles. Since its introduction, HWA has spread throughout the native range of eastern hemlocks and has altered hemlock ecosystems in the eastern United States. To learn more about this insect pest and control options available, please use the links provided in the resource library below.

The Hemlock Woolly Adelgid Treatment Cost-Share Program provides assistance for treating individual hemlock trees.


Additional Resources

ImageTitleIDDescriptionContent TypeViewhf:tax:document-categoryhf:tax:Media
Biology and Management of the Hemlock Woolly Adelgid in the Eastern U.S.
Biology and Management of the Hemlock Woolly Adelgid in the Eastern U.S.SREF-FH-012

Hemlock wooly adelgid (HWA) is a small insect that causes huge problems. Learn more about this insect in this publication including information on how to identify it, its lifecycle, and distribution as well as the damage it causes and tactics for managing it. This Southern Region Extension Forestry publication provides additional information about the biology and management of HWA.

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Hemlock Tree Management - Protection from the Hemlock Woolly Adelgid
Hemlock Tree Management – Protection from the Hemlock Woolly AdelgidFT0063

Forestry topic information sheet discusses treatment options to protect hemlock trees from the damaging hemlock woolly adelgid.

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Hemlock Woolly Adelgid Biology and Management in the Southeastern U.S.
Hemlock Woolly Adelgid Biology and Management in the Southeastern U.S.

Webinar about HWA biology and management in the Southeastern U.S.

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Hemlock Woolly Adelgid Soil Drench Treatment
Hemlock Woolly Adelgid Soil Drench Treatment

Video on how to treat hemlock trees using the soil drench method.

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Hemlock Woolly Adelgid Treatment Cost-Share Program - Application Process and Information
Hemlock Woolly Adelgid Treatment Cost-Share Program – Application Process and Information

Document provides guidance through the application process for the Hemlock Woolly Adelgid Treatment Cost-Share Program offering financial assistance for treating hemlock trees.

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Hemlock Woolly Adelgid Treatment Cost-Share Program Application
Hemlock Woolly Adelgid Treatment Cost-Share Program Application6.07

Application form to be completed to apply for Hemlock Woolly Adelgid Treatment Cost-Share Program.

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Integrating Chemical and Biological Control of the Hemlock Woolly Adelgid: a Resource Manager's Guide
Integrating Chemical and Biological Control of the Hemlock Woolly Adelgid: a Resource Manager’s GuideFHAAST-2018-04

A non-native invasive insect, the hemlock woolly adelgid (HWA), threatens the ability of natural resource managers to maintain eastern and Carolina hemlocks as critical components of unique forest ecosystems in eastern North America. Although substantial progress has been made in both chemical and biological control of HWA, neither of these tactics applied alone are expected to provide adequate control of HWA throughout its introduced range. This guide presents a methodological strategy for integrating biological and chemical control together in the same forest stands.

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Optimized Insecticide Dosage for Hemlock Woolly Adelgid Control in Hemlock Trees
Optimized Insecticide Dosage for Hemlock Woolly Adelgid Control in Hemlock Trees

Hemlock woolly adelgid (HWA) (Adelges tsugae) is killing hemlock trees in the eastern U.S. This invasive insect is native to Japan and has been in the eastern U.S. since the 1950’s. HWA feed by sucking fluids from hemlock twigs just at the base of the needles, depleting the tree of needed energy reserves. Large swaths of hemlock forests have been decimated by HWA, and millions of hemlocks have died. This publication provides information about optimized dosage for HWA control in hemlock trees

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