Hemlock woolly adelgid – Adelges tsugae (Annand)

Damage - Adelges tsugae (Annand), Hemlock Woolly Adelgid

Hemlock woolly adelgid is an aphid-like insect that attacks and kills hemlock trees. Its egg sacs, which look like cotton balls or clumps of snow, can be found at the base of needles. It can be spread by wind, animals and human movement of nursery stock, logs, firewood and other wood products. Hemlock woolly adelgid was first reported in Canada in British Columbia in the 1920s, and in the United States in the 1950s.


  • Niagara Falls, Ontario: 2013, 2015, 2019
  • Southwestern Nova Scotia: 2017
  • Wainfleet, Ontario: 2019
  • Fort Erie, Ontario: 2021
  • Pelham, Ontario: 2022
  • Grafton, Ontario: 2022
  • Hamilton, Ontario: 2023
  • Halifax County, Nova Scotia: 2023 and 2024
  • Haldimand County, Ontario: 2023
  • Hants County, Nova Scotia: 2023
  • Lincoln, Ontario: 2023
  • Port Colborne, Ontario: 2024

Regulated areas

British Columbia

Fort Erie, Ontario

Niagara Falls and Wainfleet, Ontario

Nova Scotia


Policy directive