Weevil invasion chews through Nova Scotia's beech trees

A tiny insect is eating its way through Nova Scotia's beech trees, but scientists hope a treatment could be approved this fall to help slow the invasion.

Jon Sweeney, a research scientist with the Canadian Forest Service, says the province has had beech leaf mining weevils possibly as far back as 2006. Trees infected then are dying now.

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"When the populations are high, it almost looks like the foliage has been scorched," he said.

Sweeney said by fall 2015 there was "quite a bit of mortality," especially around Bedford.

In 2014, scientists monitored areas with a lot of the insect (Bedford), areas known to have a few (Oakfield Provincial Park) and those that were clear (Mount Uniacke). 

Weevels have been reported in Wolfville and Cape Breton. Sweeney hopes it doesn't spread to New Brunswick's capital, where he is based. "We have a lot of beech in Fredericton and in Odell Park, a beautiful park in town, that we may lose a lot of beech if we get the beech weevil here."

The weevil mines beech trees and extracts nutrients from the leaves — that's the blotch. They return year after year, adding up the cost, and finally trees die under the pressure.

"There was a big difference between 2014 and 2015," Sweeney added. "It probably really represents cumulative weakening of the trees with the sustained defoliation of the weevil."

Don't move firewood

The pests can move between trees, but occasionally humans unknowingly act as a bus for the two-millimetre creature. "They can be on you, in your pocket, on your car, and you drive to a place and it might get established that way," Sweeney said. "It's not great news."

They can also hide out in firewood, reinforcing the need to buy firewood and burn it in the same area. "Please don't move firewood," he said.

While currently nothing is stopping the spread of the weevil, Sweeney and his colleagues have hope for an insecticide that's been under testing and could be cleared for use on beech trees this year. It's called TreeAzin and could help contain the weevil. 

"I'm hoping it's not too late for people in Halifax or Cape Breton, but we don't know yet," he said.