Asian giant hornet nest eradicated in east Blaine three times larger than last year’s nest

State entomologists eradicated an Asian giant hornet nest with nearly 1,500 hornets in various life stages in east Blaine the morning of August 25. The nest was three times the size of the first nest found just two miles away in October 2020.

The Washington State Department of Agriculture (WSDA) vacuumed worker hornets from the nest at the base of a dead alder tree August 19, WSDA managing entomologist Sven Spichiger said in an August 26 press conference.

WSDA transported the nest to Washington State University’s Bellingham extension for analysis. Entomologists discovered the nine-comb nest contained 292 eggs, 422 larvae, 563 cap cells (hornets about to be produced), 195 workers netted and vacuumed out during the eradication and one queen, Spichiger said. No male hornets were found.

In total, the nest contained 1,473 individual life stages, compared to last year’s six-comb nest that had nearly 500 hornets in different life stages. Genetics from the two nests haven’t been tested yet.

The hornets were more aggressive than last year’s nest and attempted to sting entomologists, Spichiger said. Because the tree was rotted, the hornets were able to create a second opening that allowed them to leave the nest after scientists sealed off the main entrance.

“We’re all very happy to say our hornet suits worked really well and no injuries were sustained,” Spichiger said of the foam suits thick enough to block a 6-mm stinger. Entomologists then blocked the second entrance and caught the escapees by net.

Warmer weather, Spichiger estimates, is the reason the hornets weren’t docile as last year’s eradication, which took place during freezing temperatures.

All of the hornets were removed within a few hours, Spichiger said.

Paul van Westendorp, provincial apiculturist for B.C., said the large nest is likely three times larger than last year’s nest, found two months later in the season, because the hornets had more food availability this summer.

“Lack of food means the nest will remain small, along with other variables, but total size of colony by the end of the season is likely due to this nest’s success in accessing food,” van Westendorp said.

Spichiger couldn’t say why this year’s nest is larger, but believes it shows the area is habitable to the invasive hornet and the weather may have been more favorable.

On August 11, an east Blaine landowner reported a photo of an Asian giant hornet eating a paper wasp nest on the eaves of their house. After the reporting, WSDA – with help of USDA’s Animal Plant Health Inspection Service (APHIS) and Oregon Department of Agriculture – attempted to track three live hornets between August 11 and August 17. The third hornet brought scientists to the nest found one-quarter of a mile away from the initial detection.

The hornets were observed raiding paper wasp nests hidden from view, which Spichiger said shows the hornets are using smell, as well as vision, to locate the paper wasps. On August 12, a landowner observed the hornets mass attack a paper wasp nest, similar to how the hornets are famously known to slaughter and decapitate a honeybee hive in a matter of hours.

“An entire group of hornets attacked one of the paper wasp nests and the behavior they exhibited was they were simply gathering all of the paper wasps, chopping their heads’ off, dropping them to the ground and then harvesting from that paper wasp nest,” Spichiger said. “This is not what was experienced throughout the rest of the neighborhood where we were seeing individual hornets harvest from other paper wasp nests and not pay too much mind to the paper wasps that were still there.”

Using live hornets from the eradicated nest, a USDA researcher is testing paper wasps to be used as a potential lure for traps, Spichiger said. WSDA will destroy the rest of the live hornets in the nest.

WSDA has received no reports of honeybee attacks since the hornets were suspected of slaughtering a Custer honeybee hive in fall 2019.

On August 20, another east Blaine landowner took a photo of an Asian giant hornet they watched attack single honeybees on sunflowers.

In 2019 and 2020, the state agency received four unconfirmed reports of Asian giant hornet stings that matched the physical reaction of a sting, including intense pain, overwhelming swelling and even led to one person being out of commission for a few days. The unconfirmed stings include a north Whatcom County beekeeper in October 2019 and a nurse who had three stings a mile from the first nest in October 2020, WSDA spokesperson Karla Salp said in an email to The Northern Light.

“They really had all of the hallmarks of being Asian giant hornet, but we are not medical doctors and the individuals were not able to collect a specimen that had to deal with these stings,” Spichiger said. “It’s nothing that can be confirmed. It’s entirely possible they were stung by native [insects].”

In San Francisco, a CBP agriculture specialist found a dead hornet on a ship deck, which will now be included in the Smithsonian’s Asian giant hornet collection, a USDA APHIS spokesperson said. The federal agency works with CBP to prevent more Asian giant hornets from being introduced to the U.S. by trade.

WSDA is not aware of additional nests, but continues trapping in Whatcom County.

“I’m glad we haven’t had hits in Birch Bay or Custer this year,” Spichiger said. “We’ve had those areas covered pretty well because we had reports last year that never went anywhere.”

Scientists first detected the Asian giant hornet in the U.S. in late 2019. The apex predator can grow up to 2 inches and has an orange-and-black body with large, almond-shaped eyes.

To report a suspected Asian giant hornet detection, visit agr.wa.gov/hornets, email hornets@agr.wa.gov or call 800/443-6684.