B.C. and Washington state collaborate to eradicate giant hornets

By Shannon Waters March 18, 2021

Agriculture officials in B.C. and Washington state are gearing up for a summer of trapping, tracking and destroying invasive Asian giant hornets on both sides of the border.

The insects have been found in several locations in southern B.C. over the past few years, including a nest that was identified and destroyed near Nanaimo in 2019.

The giant hornets pose a public safety threat: disturbing a nest can result in “a very strong, strong defensive” response from its occupants and people have died after being attacked by Asian giant hornets.

The apex insect predators are also a threat to local honeybee populations with the potential to disrupt both natural ecosystems and agriculture operations, Sven Spichiger, a managing entomologist with Washington state’s Department of Agriculture told reporters.

The hornets’ top predator status is both a boon and bane for the officials trying to track them down. Their populations tend to naturally stay fairly small, which is good news for their prey but can make them hard to find.

“They will be there and they’re very dangerous when you actually run into them, but the number of them is going to be very limited and that is in fact one of the main reasons we have so much trouble finding these darn nests, because there are so few of them around,” Paul van Westendorp, an apiculturist with B.C.’s agriculture ministry, told reporters.

Last year, six of the giant hornets were seen in the Fraser Valley, according to van Westendorp. “Comprehensive surveys” of both areas will be conducted this year in the hopes of eradicating any that remain.

Washington state detected 31 Asian giant hornets last year, thanks largely to the efforts of volunteer trappers. Officials also located and destroyed a nest containing more than 500 insects, including 200 “brand new virgin queens” capable of founding new colonies.

Officials have not yet determined how the hornets initially arrived on the West Coast or whether multiple species are currently present.

Trapping efforts will be aided by ‘magic elixir’ and Kevlar thread
Traps baited with either orange juice, a mixture of brown sugar and water, or rice wine will be set in B.C. and Washington in an effort to lure any insects that have overwintered in the Pacific northwest. Washington state’s agriculture department is also providing a “magic elixir” of pheromones to tempt the hornets into traps.

Officials plan to radio tag some of the hornets in the hopes they return to nest sites, which can then be destroyed.

Learning from past mistakes, researchers plan to use Kevlar thread to attach the tags — hornets were easily able to chew through the dental floss used last year.

“It’s really annoying to tie a tag onto a hornet, so to watch her chew it off in a few seconds is disheartening,” according to a Washington state researcher.

British Columbians who think they see an Asian giant hornet should report the sighting to the Invasive Species Council of B.C.