The venomous northern black widow spider is moving north.

So say researchers from McGill University, the Insectarium, and the Université du Québec à Rimouski, who are using photographs taken by members of the public as evidence that the arachnids are now being seen much more frequently, much further north than their habitual territory.

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“Northern black widows were known to range all the way to Belleville, just south of Kingston in the 1990s,” explains Maxim Larrivée of the Montreal Insectarium, one of the researchers looking into the migration. “They’ve been in Southern Ontario and the Great Lakes for quite a long time, but to have them all the way to Montreal and everything — now it’s not surprising, 20 years ago it would’ve been surprising.”

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Research models are predicting the spiders have moved almost as far north as Three Rivers. He credits longer and warmer summers for them to be able to survive further north. Also, it’s not only the spiders that have expanded their range further north. Larrivée adds that new species of moths and butterflies are also now calling Southern Quebec their home.

“This is a growing trend that we’ve documented since the early 2000s, for sure.”

With its legs extended, the spider is about the size of a quarter. It is dark with three red spots on the top of the abdomen and two red triangular shaped dots on its belly. Larrivée says they have an important role as bio-control agents, regulating insect population. They pose very little danger to humans.

“People should not kill spiders, ever,” he stresses. “If they are there, it’s because they are eating something else, some other insect that is present in your backyard. They are actually helping you to control other insect populations.”

He says the bite on a healthy person can result in muscle cramps and fever, but that encounters with people are extremely rare. They tend to live outside under rocks and logs and dark areas.

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“I would advise caution on the road much more than being on the lookout for black widows,” he laughs.

If you find one, he says, just admire it and leave it alone. It’ll go about its business.