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Emerald Ash Borer

Emerald Ash Borer

(Agrilus planipennis)


The insects are a bright emerald green on their back with a copper underside. They can grow to be around ½ an inch in length. The adults are not the threat, but rather the larvae stage insects cause the problems. The larvae live under the Ash trees bark layer and make S-shaped channels that disrupt the trees sap flow. Causing the tree to die, and it is around a 99% death rate of trees who become hosts to this invasive species. 

These beetles came into North America around 1990 and spread into Ontario in 2002. As Ontario had an abundant Ash population, these beetles decimated woodland cover throughout the region. Signs of an infected tree are a thinning leaf cover, an abundance of new growth at the tree base and D-shaped exit holes in the bark.

There are not many native threats to the ash borer but woodpeckers do hunt the larvae. 


The emerald ash borer covers most of southern Ontario and Quebec but also inhabits New Brunswick, Nova Scotia and some parts of Manitoba. They inhabit the majority of the eastern US.

Impacts & Control

These beetles have absolutely decimated the ash populations in southern Ontario, thinning out many of our forests. Leading to a decrease in forest diversity and habitat loss. They also have an impact on our economy as the lumber industry is affected by a loss of ash trees. Many Municipalities have spent millions of dollars removing all the unsafe dead ash trees from areas such as community parks and walking trails. As they must be cut down before they naturally fall and damage property and or kill someone.


There are various controls that aim to limit the spread of the ash borer. Since the adults can only fly a 15km range, their spread is somewhat limited. There are now imposed laws on the transport of firewood specifically old ash firewood. It is now illegal to transport this wood out of small proximity. There are also trapping methods to see if you have ash borers in your ash trees, if you do then there is a reporting service listed on the previous page.