Parasitic wasps may be 'only hope' against emerald ash borer

Montreal's environment department is hoping to defend ash trees from the emerald ash borer by sicking a tiny exotic Asian insect on them.

The Canadian government said the green beetle from China has killed millions of ash trees throughout North America, including many in Quebec. It kills them by cutting off the trees' sap circulation.

So the city is trying out parasitic Chinese wasps — a sworn enemy and devourer of the ash borer's larvae.

"We are realistic, so we know that there are ash trees that will die. But we must try this strategy because it's maybe the only hope in North America," said Maryse Barrette, a researcher working with the city.

McGill University entomologist Christopher Buddle is optimistic, but said exposing species to their natural predator doesn't always work.

"Sometimes the species you bring in just can't handle the environmental conditions in the area," Buddle said. "Species may not survive or do as well."

Barrette said the city won't know how successful the experiment here will be for at least a couple of years.