CITYnews halifax : Nova Scotia facing outbreak of ‘damaging’ spruce budworm

CITYnews halifax / By Natasha O’Neill

The province is warning that an outbreak of a worm on Cape Breton Island is quickly spreading, prompting the government to put insecticide in the area.

The spruce budworm is described by the Canadian government as the most widespread and damaging defoliator of coniferous trees in North America. The Nova Scotia government says that outbreaks have happened before in the province, and the “effects were devastating.”

Sean Power, manager of private land programs, scaling, and forest health, with the Department of Natural Resources, told Nova Scotia Today that the last major outbreaks happened in the early 70s and late 80s. In those decades, the worm damaged about two million hectares of forest from Cape Breton to Digby.

“We do have that natural population that stays very low, and then that cycle kicks in that 30 to 40-plus-year cycle,” he said. “And then the population just starts, really starts rising.”

Another way in which the worm starts becoming a larger issue is when there are migration events, Power said. They can travel through the wind from other provinces or territories.

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For the 2026 incident, Power said that the population has grown, not migrated.

To combat the issue, the province is applying bacillus thuringiensis kurstaki — also known as Btk — on a targeted area. In a press release, Dr. Robert Strang, Chief Medical Officer of Health, said that it is a biological microbe used for decades worldwide.

“It has been studied extensively and been approved by Health Canada for organic farming,” he said. “Btk only affects specific insects in the larval stage because of their alkaline gut. It does not have the same effect in humans or other animals and has been scientifically proven to be safe for other species.”

Attacks on white spruce

The worm is a moth native to Canada and found in western Canada. The Canadian government feeds on Douglas-fir trees in British Columbia, but also “attacks” white spruce, Engelmann spruce, grand fir and subalpine fir trees.

It does have natural predators and diseases that help keep the population low, but climate might play a role in controlling the numbers of the worms.

It feeds on the shoots and needles of the trees that are encased in silk, causing the defoliation of the pines. After years of the pest, the trees will die off.

Defoliation caused by the western spruce budworm near Marshall Creek, British Columbia. (Government of Canada)