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Poster: Hemlock woolly adelgid

Crown dieback, hemlock cone, infested hemlock

The hemlock woolly adelgid (HWA, Adelges tsugae) is a destructive pest of eastern hemlock, an ecologically significant tree species in eastern Canada. Eastern hemlock provides nutrients, soil stability and habitat for animals and plants.

HWA feeding removes plant fluids, causing needle drop, twig dieback and tree mortality in as few as 4 years. Early detection of HWA is critical to protecting Canada's forests and environment.

Signs and symptoms of this pest include:

  • cottony, white egg sacs at base of needles
  • as infestations advance, swelling at twig tips, twig dieback, grey foliage, stand level defoliation will occur

You can help protect natural areas from this invasive insect:

  • check hemlock trees for evidence of HWA
  • collect or photograph suspect HWA specimens if found
  • report suspect HWA or HWA damage

For more information on this subject or to report sightings please visit plant pests and invasive species.

Actual size

Cottony sacs at base of needles, 3 to 6 mm
Cottony sacs at base of needles, 3 to 6 mm

Not hemlock woolly adelgid

Image - Spittle bug
Spittle bug
Image - Spider egg sac
Spider egg sac
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