Emerald Ash Borer

Image of an Emerald Ash BorerThe Emerald Ash Borer is a highly destructive, non-native beetle species. It poses a serious economic and environmental threat to both urban and forested areas across North America, affecting ash trees in the United States and in Ontario. While the adult beetles consume the leaves of ash trees, the bulk of the damage is caused by the larvae, which feed on the inner bark of the trees. This damage to the bark disrupts the tree’s ability to efficiently transport water and nutrients. The Emerald Ash Borer poses no direct risk to human health.

EAB was initially discovered in southeastern Michigan, followed by Canada in the summer of 2002. It is thought that the insect hitched a ride to North America within the wood of packing crates. EAB has also reached Europe and ash is facing similar threats in Europe; ash in Europe is facing a double attack of disease and EAB impacts.

Image of an Emerald Ash Borer TreeThe Emerald Ash Borer has been confirmed throughout much of central and southern Ontario and Quebec.

The only way to prevent EAB is to chemically treat trees before they are infested and to annually continue to chemically threat those trees. Conservation Halton is treating around 200 ash trees to maintain them through the challenge with EAB. Conservation Halton forestry staff now believes that all ash trees in the watershed will be impacted by EAB to one extent or another and no more trees are being treated. 

The good news is ash is a rapidly regenerating species. While ash is common in our woodlands, we are managers of a diverse forest with many different tree species, so even in areas with the most ash cover, they account for only 10 to 15% of the forest. This means even when all the current ash trees are gone, there will still remain a healthy and vigorous forest.

In some urban areas where urban woodlots were established with ash as a rapidly growing single species woodlot, ash can make up more than 70% of the forest cover and these woodlands will essentially be removed and have to be re-established with new species.

One of the main ways in which EAB and other forest pests can be spread is through the movement of wood from one area to the other. To help prevent the movement of invasive species from one area to another please do not transport firewood, you could inadvertently help spread an invasive species!

What Is Being Done?

Additional Information and Photographs