Murder hornets don’t pose undue threat to the East Coast

by Emily Leeson

So-called “murder hornets” made their debut in Canada back in August 2019 when three of the large insects were found in the Nanaimo area of British Columbia’s Vancouver Island. Canadian and international experts confirmed that they were Asian giant hornets (Vespa mandarinia). It was the first time the hornets had been found in the area. 

This spring, the B.C. government is asking Vancouver Island residents to be on the lookout for more of the invasive species, and across Canada a buzz has been created about the potentially destructive insect. 

Is there any threat to the East Coast? 

“Currently, not at all,” said Dr. Stephen Heard, an evolutionary ecologist and entomologist at the University of New Brunswick in Fredericton, adding that they could eventually make their way here. “International trade brings non-native species from all over the globe despite policies and procedures that reduce this risk.”

The Asian giant hornet (AGH), which is the world’s largest hornet, is native to the more temperate climates of Asia. The worker hornets average about 3.5 centimetres long, while the queens are bigger.

The hornets feed primarily on large insects such as honeybees and are the only species of social wasp known to use scent to direct a colony to a food source. A single scout hornet, having found a honeybee hive, can lead others to it and attack as an organized group, killing the majority of the hive relatively quickly.

“In the fall, the Asian giant hornets need large quantities of protein, so they find honeybee colonies and feed on the bees and also the larvae within the nest,” explained Dr. Christine Noronha, a research scientist and entomologist with Agriculture and Agri-Food Canada in Charlottetown.

The hornets potentially pose a bigger threat to humans than the native bees and domestic European honeybees found in North America. Their stingers, which average about six-millimetres long, contain venom which, if received in a high dose (far more than a single sting), could be lethal to people besides those who are allergic to it.

However, Noronha clarified that “they are not aggressive to humans and will only attack if provoked.”

Heard said that even if the hornets were to arrive in Atlantic Canada, a local population would be unlikely to explode.

“There’s no guarantee, but the Asian giant hornet is mostly distributed in much warmer – warm-temperate to tropical – places and those parts of its range are also the most likely sources for individuals travelling by international trade,” he said. “So, individuals arriving here would most likely be adapted to much warmer conditions, unlike our native pollinators which have evolved to tolerate our harsher winters.”

However, Dr. Robyn McCallum, apiculturist and program lead with the Atlantic Tech Transfer Team for Apiculture (ATTTA), said that even the potential threat to local honeybee populations is concerning. 

“One concern is that European honeybees have not evolved to have a natural defence mechanism against AGH like other strains of honeybees,” said McCallum. “The same would go for our wild bee populations – of which there are roughly 4,000 species in North America.”

Bees in the areas in which the Asian giant hornets are native have strategies to evade the predator. North American bees, which have not co-evolved with Asian giant hornets, don’t possess those strategies. They could essentially be sitting ducks to the invading species.

While news of the “murder hornets” in North America has been somewhat overblown, McCallum said that the press coverage does have a silver lining.

“One positive note emerging from these sensationalized stories is the increased attention being placed on invasive species,” she said.

Still, McCallum said we should keep things in perspective, explaining that Atlantic Canadian beekeepers work hard managing their bees and are used to facing challenges such as harsh winters, cold and wet springs, dry summers, and various diseases and pests.

“It’s important to keep in mind that beekeepers already deal with wasps and hornets in bee yards,” she said. “In fact, wasps and hornets can be quite serious in bee yards in the fall, especially with weak honeybee colonies. If Asian giant hornets were to reach Atlantic Canada, and this is probably unlikely, beekeepers would continue to adapt management strategies to keep honeybees strong and healthy.”