Emerald Ash Borer

Identification & Biology
Alias' : EAB
Latin Name : Agrilus planipennis
Category : Insects & Spiders
Description :
  • Adults are metallic blue-green 
  • Narrow, hairless, and elongate 
  • 8.5 to 14 mm long and 3.4 mm wide 
  • Eyes are bronze or black 
  • Mature larvae are 26-32 mm long and creamy white 


The emerald ash borer (EAB) is a species of metallic wood-boring beetle that kills ash trees (Fraxinus spp.). It was first detected near Detroit, Michigan and Windsor, Ontario in 2002, and since then has spread to more than 35 states and 5 provinces. EABs generally have a one-year life cycle. Eggs are laid on the bark of ash tree branches through summer and hatch into larvae after two weeks. Larvae tunnel through the ash tree feeding on the inner bark and sapwood, leaving behind galleries (s-shaped tunnels) filled with a fine brownish coating. Most larvae mature during the fall then overwinter in the ash trees. In the spring of the following year, the larvae will pupate and transform into adults. Adult EABs spend most of their time feeding on ash leaves in the ash canopy and will mate and lay ~40-70 eggs about 3-4 weeks before dying. 


Native to East Asia, the emerald ash borer prefers to live in forested areas that contain species of ash trees. EABs will complete their entire lifecycle on ash trees. They were first detected in the U.S.A. in Michigan in 2022, and since have spread to at least 35 states and 5 provinces. They were recently detected in the Pacific Northwest for the first time in June 2022, in Forest Grove, Oregon. EABs have not been found yet in British Columbia, but populations exist in Manitoba, Ontario, southern Quebec, New Brunswick, and Nova Scotia in Canada.

Impact & Risks
  •  EABs pose a major economic and environmental threat to urban and forested areas across Canada. 
  • The EAB is a highly destructive beetle which attacks and kills all species of ash (note – not mountain ash; despite its name, this is a different species of tree). Up to 99% of all ash trees are killed within 8-10 years once the beetle arrives in an area. 
  • Ash trees provide important food and habitat along streams, rivers, and wetlands. Loss of ash trees can result in changes to soil chemistry and gaps in the tree canopy, which can lead to increased soil erosion, higher stream temperatures, and changes in community composition and function. 
  • Though ash trees are not native to much of British Columbia and Alberta, non-native trees have been planted in many cities. Ash trees contribute to a city’s aesthetic value and provide shade, and ash wood is used to make furniture, hardwood floors, baseball bats, tool handles, and more. 
  • Signs and symptoms of an EAB attack include weak and thinning ash crowns, branches with yellowing leaves, bark splits, and D-shaped exit holes on the trunk. Woodpecker activity may also indicate the presence of EABs. 
Prevention & Mitigation
  • EABs can be spread from transport of infested ash nursery stock, logs, and firewood. Movement of ash logs and firewood out of regulated areas is restricted. 
  • “Buy it where you burn it”. Don’t move firewood and buy certified heat-treated (kiln-dried) where available. 
  • Learn to identify the EAB and educate your neighbours, friends, and family about the risks. 
  • If you see suspected signs of an infestation on your ash trees or if you plan on moving firewood, contact the Canadian Food Inspection Agency (CFIA) for more information. 
Treatment & Disposal
  • The Canadian Forest Service (CFS) has developed trapping methods for early detection, conducted research to introduce parasitic wasps as biocontrol, investigated using a naturally occurring fungus that is potent against EAB to control populations, and developed the botanical insecticide TreeAzin. For more information, visit the CFIA website. 
  • If you are in an area that is regulated for EAB and you have recently trimmed or cut down your ash tree, call your municipality or the CFIA for directions on disposal. 


For more information on the Emerald Ash Borer, view the Northwest RISCC Management Brief: Managing the Threat of Emerald Ash Borer in a Changing Climate 

Okanagan Distribution

Priority Level Definitions

Watch For - Poses a significant threat (very high risk) and does NOT presently occur in the region OR is relatively new to the region and is very limited in extent.
High - High risk/impact; limited population with significant potential to spread in the region.
Medium - Medium risk/impact; limited distribution – broader population distribution with potential to spread further in a region.
Low - Low risk/impact; may be widespread or not, may be of concern in specific situations with certain high values – e.g. specific agriculture crops. Some species may be treated primarily with biological control agents.