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Emerald Ash Borer

Agrilus planipennis
Home 9 Invaders 9 Forest Pests & Pathogens 9 Emerald Ash Borer


Emerald Ash Borer is a forest pest native to Asia that has killed millions of Ash trees in southwestern Ontario, and the Great Lakes States. Due to its major economic and environmental threat, the Canadian Food Inspection Agency has prohibited the movement of firewood and any material made from Ash trees outside of designated areas under an Infested Places Order.

The Emerald Ash Borer attacks both healthy and stressed Ash trees when its larvae tunnel through the tree’s vascular system which delivers water, nutrients and sugars throughout the tree. Emerald Ash Borer will only travel a few kilometers per year on its own; however it can be easily dispersed long distances by people moving infested materials, such as firewood, logs, lumber, and woodchips.


Emerald Ash Borer was first discovered in North America in 2002. It is thought to have been shipped to Canada in untreated wooden packaging materials. The range of Emerald Ash Borer in Ontario is rapidly expanding through the movement of infested materials. For an up to date range map, consult with the Canadian Food Inspection Agency.

Impacts of Emerald Ash Borer

  • Attacking both stressed and healthy Ash trees.
  • No known natural enemies to control the population or spread.
  • Once infested, mortality of Ash trees is nearly 100%.
  • Loss of habitat and food for other species.
  • Extremely harmful to urban and rural biodiversity.
  • Loss of valuable timber that is used for furniture, building and recreational products.

How to Identify Emerald Ash Borer

  • Trees appear to be thinning at the crown, dead branches and yellowing of leaves.
  • Adults emerge from a D-shaped exit hole between mid May and late June.
  • Adults are metallic blue-green.
  • Bodies are narrow and 8.5 to 14 mm long.
  • Larvae are a creamy white colour with a light brown head.

What You Can Do

  • Learn how to identify adult Emerald Ash Borer and what infested trees look like, as well as which host trees they target.
  • Don’t move infested wood material from the regulated zone to new areas; this includes all firewood, trees, logs, lumber, wood or bark chips. Firewood should always be obtained locally and burned on site.
  • If you see Emerald Ash Borer or signs of infestation, call the Ontario Ministry of Natural Resources and Forestry at 1-800-667-1940 or the Canadian Food Inspection Agency at 1-800-442-2342.
  • If you’ve seen an Emerald Ash Borer or any other invasive species in the wild, please contact the toll-free Invading Species Hotline at 1-800-563-7711 or visit EDDMapS to report a sighting.

Resource Files


OFAH/OMNRF Invading Species Awareness Program. (2021). Emerald Ash Borer. Retrieved from:
This factsheet may be reproduced for non-commercial purposes.

Header photo by Debbie Miller, USDA Forest Service,

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