Hemlock Woolly Adelgid
Insect Pest
High Threat
Photo: Robert L. Anderson / USDA Forest Service (CC-BY-3.0-US (Bugwood))
Identification & Biology
Tiny aphid-like insect from Asia that feeds on hemlock needles. Identified by white cottony masses at the base of needles. Kills trees in 4-10 years without treatment.
Current Status
Established throughout the region. Has killed large percentages of native hemlocks.
States affected:
Connecticut
Delaware
Maine
Maryland
Massachusetts
New Hampshire
New Jersey
New York
Pennsylvania
Rhode Island
Vermont
Virginia
What Homeowners Should Do
Treat high-value hemlocks with systemic insecticide (imidacloprid soil drench or dinotefuran). Biological control agents are being released in forests but aren't sufficient for individual tree protection.
Identification Photos
Related Threats
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