Although they’re still killers -- mass murderers of honeybees who have not changed their ways --- they’re no longer being referred to as “murder hornets.” Scientists call them Asian giant hornets, an invasive pest that threatens the lives of Pacific Northwest pollinators and ignores international borders in doing so.

Now the Washington State Department of Agriculture, U.S. federal officials, and British Columbia authorities have geared up to collectively track, trap, and destroy any giant hornets discovered in 2021.

“2020 was an exciting year for the citizens of Washington and we had a lot of help as 1,200 folks hung and serviced traps that ended up with 31 detections with an eventual tracking back to the nest,” said Sven Spichiger of the WSDA. Although some cells were empty, one nest yielded 500 specimens, 200 of which were virgin queens that might have set out on their own to form new colonies.

Washington’s plans this year will be similar to last year’s response with a strong emphasis on public outreach, reporting, and trapping with WSDA emphasis focused on areas in Whatcom County where the hornets were detected in both 2019 and 2020.

“We’ll be working Northern Whatcom County and in the Bellingham area with citizen volunteers setting out brown sugar and water traps to help us keep an eye on the rest of the state,” Spichiger said.

Overwintering hornets spend the cooler months in their protected cells and emerge about this time of year with queens starting to lay eggs and colonies increasing in size in July and August.  By fall, their murderous inclinations become apparent as they search for protein for new wintering nests. Residents in Whatcom, Skagit, San Juan, Island, Jefferson, and Clallam counties will start citizen scientists trapping in July.

An imaginary line

While acknowledging that “the border is an imaginary line”, Paul van Westendorp of the British Columbia Ministry of Agriculture reported the Fraser Valley made several hornet discoveries after an initial nest detection on Vancouver Island in 2019. No sightings or collections were reported in Nanaimo and the Cowichan Valley on Vancouver Island in 2020.

“Perhaps we just nipped things in time,” he said. If no sightings show up this year, Vancouver Island could be declared Asian giant hornet-free.

Calling the scope of the problem “an ongoing challenge and a formidable task,” Westendorp added: “This isn’t just a BC problem or a Washington State problem, it’s a collective problem.”  More than 100 beekeepers along the border will join detection efforts this year by setting bottle traps. “We’ve got just about everybody involved and we’ll do whatever it takes to mitigate the problem,” he said. “There are only a few apex predators like this around and climactic zones in BC prohibit much further expansion, so we have a good chance of success. Time will tell.”

Concern for the future centers not just on what species might already have arrived here from places like Japan, China, and South Korea, but the fact that the border area is prone to future possible introductions of sub-species via maritime shipments of goods from those countries. 

“In Southeast Asia, there are several regional species of giant hornets that are a delicacy commodity,” noted USDA Bee Lab Researcher Anna Childers.

Genome profiles

“We’re working on gathering and sequencing genome profiles of the hornets trying to understand their diversity and sub-populations,” added USDA honeybee expert Anne LeBrun.  “Knowing the origin is important to control efforts because it offers a better understanding of nesting biology and potential range of expansion as well as development of biological control methods.”

With larger numbers of citizen spotters joining the battle this season, WSDA’s Spichiger noted: “Our goal is eradication this year because this is not a species we want to tolerate.  If it gets well established, there could be an ecological impact as it spreads and goes after other species of insects, like slaughtering honeybee hives, and we want to protect agriculture.”

Asked how likely it was that the eradication effort could be accomplished this year, Spichiger replied: “I’m optimistic, but not naïve. It’s a daunting task.”