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National Invasive Species Information Center
U.S. Department of Agriculture
  1. Home
  2. Terrestrial Invasives
  3. Terrestrial Invertebrates
  4. Hemlock Woolly Adelgid

Hemlock Woolly Adelgid

Scientific Name

Adelges tsugae (Annand) (Annand 1928)

Common Name

Hemlock Woolly Adelgid (HWA)

Native To

Japan (Orwig et al. 2003)

Date of U.S. Introduction

Discovered on the West Coast in the 1920s, but it is disputed whether this was an introduced or native population; an introduced population was discovered on the East Coast in the 1950s (Havill et al. 2006; Orwig et al. 2003)

Means of Introduction

Accidental (Wallace and Hain 2006)

Impact

Destroys Eastern hemlock trees (Tsuga canadensis) (Orwig et al. 2003)

Hemlock Woolly Adelgid

Hemlock Woolly Adelgid, Adult with wax removed

Credit

Michael Montgomery USDA, Forest Service

Source
Invasive.org.

Find more images

Spotlights

  • ARS Research News - U.S. National Arboretum Offers Solution to Hemlock Woolly Adelgid Pest

    • Feb 23, 2023

    • USDA. Agricultural Research Service.

    • Hemlocks in the U.S. are vulnerable to attack by a small insect called the hemlock woolly adelgid (HWA). This insect looks like tiny cotton balls on the needles of the tree and can kill the trees by feeding on the sap. The adelgid has decimated stands of hemlocks in the eastern U.S. While insecticides and biological control measures can offer some relief, the best way to combat HWA is to develop genetic resistance in the trees.

  • New Manager’s Guide for Controlling Hemlock Woolly Adelgids

    • Sep 24, 2020

    • USDA. FS. Southern Research Station. CompassLive.

    • Forest Service scientists have published a guide synthesizing best practices for controlling these tiny bugs. It promotes a strategy of combining insecticide use with adelgid-eating insects.

Distribution / Maps / Survey Status

  • Vermont Forest Invasive Pest Status Map

    • Mar 19, 2024

    • Vermont Forests, Parks & Recreation. Forest Health Program

    • The newly launched Vermont Forest Invasive Pest Status Map offers an interactive platform to track the spread of invasive species such as beech leaf disease, elm zigzag sawfly, elongate hemlock scale, emerald ash borer, and hemlock woolly adelgid across the state. The application provides users with a comprehensive overview of town infestations and detection years for each invasive pest.
      See also: Vermont Forest Health Program Launches Interactive Invasive Pest Status Map

  • Alien Forest Pest Explorer (AFPE)

    • USDA. FS. Northern Research Station.

    • The Alien Forest Pest Explorer (AFPE) is an interactive web tool which provides detailed spatial data describing pest distributions and host inventory estimates for damaging, non-indigenous forest insect and disease pathogens currently established in the U.S. The database is maintained as a joint effort of Purdue University, the U.S. Forest Service Northern Research Station, and the U.S. Forest Service Forest Health Protection.

  • Early Detection & Distribution Mapping System (EDDMapS) - Hemlock Woolly Adelgid

    • University of Georgia. Center for Invasive Species and Ecosystem Health.

    • Provides state, county, point and GIS data. Maps can be downloaded and shared.

  • Pest Tracker - Survey Status of Hemlock Woolly Adelgid

    • USDA. APHIS. Cooperative Agricultural Pest Survey. National Agricultural Pest Information System.

Quarantine

Videos

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Selected Resources

The section below contains highly relevant resources for this species, organized by source.

Partnership
Federal Government
International Government
State and Local Government
Academic
Citations