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The emerald ash borer 2:22

The federal government has a new plan to fight the emerald ash borer, a pest that is decimating ash trees in Hamilton.

But it's kind of gross.

The Canadian Food Inspection Agency is in the midst of a pilot program in two types of Asian wasps to manage the population of ash borers.

The wasps don't just eat the ash borer — they lay eggs inside still-living ash borer larvae, and then about a month later, the eggs hatch, eating their way out of the other insect.

"These things are like aliens," said Jonathan Leto from the U.S. department of agriculture, who manages a facility in Michigan that grows the wasps. "They lay their eggs inside of the emerald ash borer and then later, the ash borer ruptures and all of these new wasps come out."

It's a plan that's in its early stages in Canada — but the city is "absolutely" open to using the wasps in Hamilton should it be deemed safe, says Tami Sadonoja, the project manager for forest health with the City of Hamilton.

"It's always better to have natural controls rather than chemicals," Sadonoja said.

City saving what it can

But right now, chemicals are all the city has at its disposal to fight the pest. City staffers are in the process of identifying 800 "high value" ash trees qualified for insecticide treatment, an alternative to tree removal and replacement.

Seeing as Hamilton is home to 23,000 ash trees that make up about 8 per cent of the city's canopy, that insecticide treatment isn't going to be enough. "We're seeing dead trees throughout the city right now," Sadonoja said. "We're seeing more and more mortality every year."

The wasps, which are called Tetrastichus, are about a millimeter or two long but don't actually sting. Instead of a stinger on their tail end, they have a small device which is used to deposit eggs into unwitting ash borer larvae.

They were first released in Canada early this summer, says Barry Lyons, a research scientist with Natural Resources Canada. The Canadian government is in the midst of a second release of the wasps in Huron County, Ont. Scientists will be testing the area in 2014 to see if it has been effective. They also need to know if the wasp will overwinter in Canada, "which it should do," Lyons said.

So who watches the wasps?

Many might wonder about the wasps becoming a problem and multiplying too fast, thus becoming just as troublesome as the ash borer itself.

But Lyons says that this wasp is so particular about its prey that it shouldn't be an issue. In fact, when U.S. scientists provided the wasp with other beetle larvae similar to the ash borer as a test, it wasn't interested.

"This particular wasp is very species-specific to the ash borer," Lyons said. It also shouldn't be a problem for humans, as it doesn't have a stinger.

Last September, the city adopted a $26.2-million action plan that will gradually chop down Hamilton's ash trees because of the emerald ash borer. $100,000 per year will go toward injection treatments, while $1.6 million will go toward removal and replacement. Each injection costs $250 and has to be repeated every other year for the insecticide to be effective.

Lyons cautions that the wasp treatment wouldn't be "silver bullet" to save ash trees everywhere. It could be a few years before the program is spread outwards to municipalities.

But the city is still hoping it could be a big help, "provided it's not too late for us," Sadonoja said.