Title: Hemlock Woolly Adelgid (Pest Alert)
Author: USDA Forest Service
Publication: US Forest Service, Northeastern Area, State and Private Forestry, 11 Campus Blvd, Quite 200, Newtown Square, PA 19073, NA-PR-09-05
Abstract: Native to Asia, the hemlock woolly adelgid (Adelges tsugae) is a small, aphidlike insect that threatens the health
and sustainability of eastern hemlock (Tsuga canadensis) and Carolina hemlock (Tsuga caroliniana) in the Eastern
United States. Hemlock woolly adelgid was fi rst reported in the Eastern United States in 1951 near Richmond, Virginia.
By 2005, it was established in portions of 16 States from Maine to Georgia, where infestations covered about half of the range of hemlock. Areas of extensive tree mortality and decline are found throughout the infested region, but the impact has been most severe in some areas of Virginia,
New Jersey, Pennsylvania, and Connecticut.
Hemlock decline and mortality typically occur within 4 to 10 years of infestation in the insect's northern range, but can occur in as little as 3 to 6 years in its southern range. Other hemlock stressors, including drought, poor site conditions, and insect and disease pests such as
elongate hemlock scale (Fiorinia externa), hemlock looper (Lambdina fiscellaria fiscellaria), spruce spider mite (Oligonychus ununguis), hemlock borer (Melanophila fulvogutta), root rot disease (Armillaria mellea), and
needlerust (Melampsora parlowii), accelerate the rate and extent of hemlock mortality.
Online Access: http://na.fs.fed.us/spfo/pubs/pest_al/hemlock/hwa05.htm
High resolution document suitable for printing: http://na.fs.fed.us/spfo/pubs/pest_al/hemlock/hwa_05.pdf
Portable Document Format (.pdf) files need a free reader, available here.
Return to Publications