Fauna
Insect · GBIF taxon 2049739

Hemlock Woolly Adelgid

Adelges tsugae

Also known as HWA, Hemlock Adelgid

Hemlock woolly adelgids spend most of their lives attached to the base of hemlock needles, secreting a dense, white waxy coat that resembles miniature cotton swabs. By inserting needle-like mouthparts directly into twig tissue, these tiny insects drain vital nutrients and disrupt water flow, causing needle loss, branch dieback, and eventual tree death within a few years. While natural predators keep populations in check across East Asia and western North America, unrestrained outbreaks in the eastern United States continue to reshape entire forest ecosystems.

InvasivePestSap-sucker
Hemlock Woolly Adelgid reference1 / 7
Licensed reference(c) Douglas Goldman, some rights reserved (CC BY-SA), uploaded by Douglas Goldman · cc-by-sa
—observations
—countries
—peak records
Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Key facts
Diet & prey
  • Eastern hemlock sap
  • Carolina hemlock sap
  • Spruce tree sap
Predators
  • Sasajiscymnus tsugae
  • Laricobius nigrinus
  • Leucopis flies
ThreatsExtreme winter cold and biological control programs using predatory beetles
HabitatsTemperate coniferous forests, forest valleys, urban parks
Life span1–6 months
Classification
  1. FamilyAdelgidae
  2. SpeciesAdelges tsugae
Range & activity
Range data is not available yet.
Safe observation
Interaction riskLow
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is low
Safe to observe at a normal distance.
Responsible observation
  • Inspect underside of branches: Look for tiny white, cottony masses clinging to the base of needles.
  • Report infestations: Alert local forestry offices when finding white waxy sacs in uninfested counties.
  • Avoid spreading pests: Refrain from moving hemlock firewood or wild-harvested trees from infested areas.
Related species
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