Tens of thousands of trees in Montreal are facing a deadly threat from the tiniest of attackers.
For the last few years an Asian beetle called the Emerald Ash Borer has been eating its way through Quebec's ash trees and efforts are underway to slow the beetle's spread on the island of Montreal.
While the ash trees that line avenues and grow in parks across the island of Montreal may look healthy many are being eaten from the inside out.
For two years researchers have been setting traps across the island to look for the Emerald Ash Borer, trying to pinpoint where the bug is while populations are still relatively low.
These metallic-green beetles may be tiny but they will kill any ash tree they encounter.
The females lay their eggs in the trees, and when the eggs hatch the larvae bore their way between the bark and the wood in the tree's cambium.
After three or four months as grubs, the fully-grown adults emerge from tell-tale D-shaped holes, and can fly up to one kilometre to find another tree.
Dr. Robert Lavallee of Natural Resources Canada says the larvae kill the tree by cutting off the flow of sap.
"It's the only living part of the tree. A tree is very fragile and this insect lives there and they eat all this tissue. So doing this way they will simply cut the way to the sap to move in the tree," said Dr. Lavallee.
The Emerald Ash Borer was first spotted in Ontario in 2002 and appeared in Carignan, Quebec in 2008, often being spread by people moving firewood from home to campsites.
Two years ago the beetle spread to the island of Montreal, and experts say it is impossible to truly stop the bug.
"We have to forget the idea of controlling the insect. It won't be possible. But what we expect is to slow down the process of the population build-up," said Dr. Lavallee.
The city of Montreal and some neighbouring municipalities are doing this by tracking down infested trees and cutting them down.
Adjacent trees are then treated with a product called Tree Azin that works much like a vaccine. Arborists drill holes in a ring around the base of the tree and inject a liquid pesticide which affects the beetles' reproduction and shortens their lives.
Treating a single tree costs $200 and the process must be repeated every other year, which is far cheaper than the $5500 it costs to cut down and replace a mature tree.
"Trees will benefit everything from property values to the air we breathe so they're important to keep if we can," said Elizabeth Ulin, a councillor in Montreal West.
Meanwhile researchers are continuing to track the insect and experiment with ways to limit its impact.
One tactic approved by the Canadian Food Inspection Agency is the importation and release of two species of Asian parasitic wasps. Woodpeckers will feed on the Emerald Ash Borer, but there are not enough to control the population -- whereas in Asia wasps will attack the borers and lay eggs in their larvae.
Earlier this year the CFIA agreed to bring the stingless wasps into the country -- a move that the United States is also making.
Scientists say they will do everything they can to save as many trees as possible in a war they know they can't win.
