By David Rasbach, The Bellingham Herald
Aug. 28—He’s a few years away from being able to proclaim Washington state’s threat from the invasive Asian Giant Hornet “100 percent eradicated,” but no new news is good news, as far as Washington State Department of Agriculture Managing Entomologist Sven Spichiger is concerned.
“Our data right now from trapping and reports do not suggest there are any additional nests,” Spichiger said during an online briefing about this week’s eradication of a hornet nest in northern Whatcom County, “but that’s why it’s so important for the public to keep submitting reports.”
Those reports helped lead Spichiger and his team to finding the year’s first nest occupied by approximately 1,500 Asian Giant Hornets — commonly known as “Murder Hornets” — in various stages of development last week and allowed them to eradicate it on Wednesday, Aug. 25.
The nest was found at the base of a dead, decaying alder tree in a rural area of the county east of Blaine. It was located approximately two miles from the nest that the Department of Agriculture eradicated last October, one-quarter mile from where a resident reported a live sighting of an Asian giant hornet on Aug. 11 and one-quarter mile south of the Canadian border.
Spichiger said the nine-comb nest eradicated this week was approximately three times larger than the one found last year.
Department of Agriculture staff and other partners began Wednesday’s eradication by vacuuming 113 worker hornets from the nest, according to the release. The team then removed bark from the decaying tree at the entrance to the nest, revealing that the hornets had excavated the interior of the alder tree to make room for nine layers of comb.
The portion of the tree that contained the nest was taken to the Washington State University Extension in Bellingham for analysis, according to the release.
Inside the nest, Spichiger said the team found 292 eggs, 422 larvae and 563 prepupae/pupae (also known as capped cells). The team also captured 195 workers that were all female and one queen.
“This nest was a bit more aggressive than the nest we encountered in 2020,” Spichiger said. “They were a bit more interested in what we were doing. In 2020, they barely paid us any mind.”
While they were eradicating the nest, the hornets were able to create a second entrance to the nest and escape, Spichiger said. The hornets that escaped approached the team and attempted to sting members.
“I’m happy to say that our hornet suits worked very well,” Spichiger said, referring to the suits made of soft foam covered by mesh netting that prevents the hornet’s quarter-inch stinger from reaching workers who are wearing them.
Finding and eradicating the nest this early in the year, when it was warmer out, may have had an impact on why the hornets were more aggressive this year than during last year’s nest eradication, which occurred in October, Spichiger said.
But eradicating the nest this early in the season also was important, Spichiger said, because “this time of year they’re just building up the nest before they start to switch over to reproductive tasks later in the season.”
While some of the approximately 1,500 hornets were destroyed, Spichiger said some non-breeding hornets were taken to a lab in Wapato for experimental testing. Though the team netted most of the hornets that escaped, Spichiger said any that were able to get away should die within the next few weeks due to their life cycle.
The team plans to have the DNA of hornets from this year’s nest compared to that from last year’s nest and one found in British Columbia to see how they are related, Spichiger said.
Spichiger said he is pleased that there have not yet been additional reports of Asian Giant Hornets in the Custer or Birch Bay areas, but he reminded residents in Whatcom County to continue to keep an eye out.
The Department of Agriculture showed the nest that that was eradicated last year during the Northwest Washington Fair in Lynden earlier this month, and Spichiger said the exhibition was “very well received.”
“We’re very grateful to the public that helped us with their reports this time around,” Spichiger said. “The folks that originally reported the live hornets allowed us unfettered access to their property. We really can’t get this done if people are not as helpful as they were. We’re thankful the property owners where the nest was found were so cooperative.”
Chasing ‘Murder Hornets’
The first live Asian giant hornet sighted in 2021 in Washington state was found attacking a paper wasp nest in a rural area of northern Whatcom County Aug. 11. Later that same week, the Department of Agriculture trapped and tagged three live hornets.
“Both hornets were tagged, given a pre-flight strawberry jam meal, and released,” a department Facebook post said.
Though one of the hornets was able to slip its tracker and another was never located, the Department of Agriculture announced Aug. 20 that the third hornet had led the team to the nest.
Up to 2 inches long, the Asian giant hornet, or Vespa mandarinia, is the world’s largest hornet species. They are identifiable by their large yellow/orange heads. The hornets are known for their painful stings.
They will attack people and pets when threatened. People should be extremely cautious near them, state agriculture officials have said, and those who have allergic reactions to bee or wasp stings should never approach an Asian giant hornet, according to earlier reporting in The Bellingham Herald.
The invasive hornets are feared for the threat they pose to honeybees and, by extension, the valuable crops in Washington state that the bees pollinate, including blueberry and other cane crops in the region that includes Whatcom County.
They also prey on local pollinators such as wasps, posing a threat to the local ecosystem, state entomologists have said.
A dead Asian giant hornet was located near Marysville in mid-June.
The Department of Agriculture will continue to trap Asian giant hornets through the end of November, according to Thursday’s release, adding that instructions on how to build traps can be found on the agency’s website.
The Department of Agriculture’s annual budget for community outreach, tracking and eradication of the Asian giant hornet is approximately $650,000, Spichiger said.
Spot a ‘Murder Hornet’?
Washington state residents can report possible sightings of an Asian giant hornet to the state Department of Agriculture online at agr.wa.gov/hornets, via email at firstname.lastname@example.org, or by calling 1-800-443-6684.
Take a photo or keep a specimen if you can. They’re needed for confirmation.
Citizen science trapping instructions also are on the website.
More on the department’s Asian giant hornet effort can be found at facebook.com/groups/hornets.