Insects Index
Asian Longhorned Beetle
Anoplophora glabripennis
Elm Zigzag Sawfly
Aproceros leucopoda
Emerald Ash Borer
Agrilus planipennis
Fall Cankerworm
Alsophila pometaria
Forest Tent Caterpillar
Malacosoma disstria
Hemlock Woolly Adelgid
Adelges tsugae
Ips Bark Beetles
Ips spp.
Sirex Woodwasp
Sirex noctilio
Southern Pine Beetle
Dendroctonus frontalis
Spongy Moth
Lymantria dispar
Spotted Lanternfly
Lycorma delicatula
Elizabeth Willhite, USDA Forest Service,

Hemlock Woolly Adelgid

Adelges tsugae

The hemlock woolly adelgid, originally from Asia, was first discovered in the eastern U.S. in the 1950’s.  It has since spread throughout the range of hemlock in the East, and caused extensive mortality of mature hemlock – especially in the Appalachian Mountains.  This small, aphid-like insect produces a white tuft of cotton-like substance, making them easy to see on the dark green background of hemlock needles.  Immatures, or crawlers, are only mobile for a short time during which they disperse by crawling or by wind.  Once they find a suitable spot, they insert their mouthparts into the tree and remain there the rest of their life.  Control is difficult, but high-value trees can be protected with soil-drench or stem-injectable insecticides.  Natural enemies provide some management, but many efforts now are toward developing resistant hemlock selections with which to replant areas devastated by the insect.
Biology and Management of the Hemlock Woolly Adelgid in the Eastern U.S. Southern Regional Extension Forestry - Forest Health, 2019

Environmental Risks to Arthropods from Imidacloprid Applications for Hemlock Conservation

Warnell School of Forestry and Natural Resources, University of Georgia, 2020

Hemlock Woolly Adelgid

Pennsylvania Dept. of Conservation and Natural Resources

Hemlock Woolly Adelgid

University of New Hampshire and USDA Forest Service, 2004

Hemlock Woolly Adelgid

Maine Dept. of Conservation, 2010

Hemlock Woolly Adelgid in Georgia

Georgia Forestry Commission, 2007

Hemlock Woolly Adelgid: Control Options

Georgia Forestry Commission, 2010

Optimized Insecticide Dosage for Hemlock Woolly Adelgid Control in Hemlock Trees

University of Georgia, Connecticut Agricultural Experimental Station, 2018

The Hemlock Woolly Adelgid in Georgia

Georgia Forestry Commission, 2013


Hemlock Woolly Adelgid

The Nature Conservancy and Southern Regional Extension Forestry, 2016

Hemlock Woolly Adelgid ID

USDA Forest Service
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