Trees Please Hamilton

Green Solutions to Air Pollution

TREE TUESDAY – Emerald Ash Borer

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Adult Emerald Ash Borer

Have you heard of the Emerald ash borer? It’s story is rather dramatic, definitely not a bore. The beetle was first spotted in Windsor, Ontario in 2002 – suspected to have stowed away on wood packaging from Asia. Since then it has spread, killing millions of trees in Southern Ontario, Quebec and the Northern U.S. The ash borer does not move very far on its own – it typically flies 5km in search of another host tree – but humans have assisted its spread through moving around beetle-infected firewood. 

The borers lay their eggs under the ash’s outer bark, then the larvae eat their way through the inner bark – damaging the channels through which the tree transports water and nutrients. This eventually kills the tree within one to four years of infestation. Emerald ash trees in North America are vulnerable compared to trees in Asia that have co-evolved and built up defences to these beetles. 

This infestation has an extensive impact on urban areas like Hamilton that have planted many ash trees along streets and in parks. According to the City, by 2020 all of Hamilton’s ash trees could be killed. To prevent further beetle spread, the City passed a motion in 2012 to remove or treat 10% of Hamilton’s ash trees every year for ten years. Each ash removed would be replaced with a different species to diversify our urban canopy and make it more resilient to future pest attacks. Significant ash trees are being treated with an injectable pesticide, but it is not financially possible to treat all ash trees in the City. 

While inventorying in McQuesten, we found three ash trees. This is not a common find for us, but don’t get too excited because they were all mostly dead. 

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Information from our inventory in McQuesten




Author: treespleasehamilton

A project of the Hamilton Naturalists' Club and Environment Hamilton. Funding by Ontario Trillium Foundation.

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