Entomologists with the state of Washington announced Tuesday the first nest discovered in the state contained about 500 pupae and live hornets late last month in Whatcom County.
The 2-inch-long hornets, also known as yak killer hornets or murder hornets because of their ability to kill humans, were first discovered in extreme northwest Washington state in December. Since then, the Washington state Department of Agriculture has been working to eradicate the hornets, which have not been found anywhere in the state except in Whatcom County and just over the border with Canada.
On Oct. 22, officials followed a live hornet with an electronic tracking device to a tree in Whatcom County. In the early morning hours of Oct. 24, entomologists went to the nest and used a vacuum to remove several hornets from the nest, said Sven-Erik Spichiger, the department's managing entomologist.
While traps previously had caught 20 of the hornets, the nest had about 776 cells. Of those, some 108 were capped, meaning they had queen Asian giant hornets that were ready to emerge. They also found 191 dead pupae. But they captured 112 live worker hornets and nine males, called drones.
Researchers returned Oct. 28 to dissect the hollow tree that contained the nest. Inside, researchers found 67 live queens that must have emerged after Oct. 24 but had not yet left the nest. Nearby, they found three dead queens that had left the nest but drowned in a bucket containing water.
"So we were able to get about 500 insects from this nest," Spichiger said. "If we had not intervened, we would be starting with the number of 200" potential queens that could have started new nests. "As far as we can tell, we got there just in time."
While finding the nest was a major breakthrough in the effort to eradicate the large hornets from the region, trappings in other areas around Blaine and Custer suggest researchers have at least two other nests that have not yet been located, he said.
"I'm still cautiously optimistic," Spichiger said. "If we had 17 hits in 17 counties, I'd say the genie is out of the bottle." But the trappings and nest have all been found in the same general area, suggesting that "it's a fairly contained event."
It's believed the hornets, which find a warm place to hibernate for the winter, came to the United States through international travel from Japan or South Korea, where the hornets live in the wild.
"A lot of folks in cultures in Southeast Asia prefer to fry up the (Asian giant hornet) pupae and some of the brood" as food, Spichiger said. "Some of my Facebook friends posted pictures of their harvest in Thailand. It looked pretty tasty."
But the hornets pose a danger because they can sting victims multiple times and because of their size they can inject more venom with each sting, which can cause human flesh to die around the wound and can eventually lead to organ failure, he said.
"If you walk into a nest, your life is probably in danger," Spichiger said. "But it is, too, if you step into nests of other hornets, especially if you are allergic."
While Spichiger has seen statistics indicating Asian giant hornets kill about 20 humans a year in their native range, that compares to about the same number of people killed by interactions with yellow jackets, paper wasps and bald-faced hornets in the U.S.
Efforts to eradicate the Asian giant hornet began because they compete with native hornets and one of their favorite foods is honey bees. Asian giant hornets can attack beehives, biting the heads off thousands of honey bees to get at their pupae, which are used as food at the Asian giant hornets' nests.
Beekeepers in Washington have not reported any suspected Asian giant hornet attacks in 2020.
Earlier in October, researchers used electronic trackers using Bluetooth technology. But the trackers had limited range and battery life.
Spichiger said researchers then obtained leftover radio trackers from the U.S. Department of Agriculture on the East Coast. After trapping a live hornet on Oct. 21, it led them to the nest on Oct. 22.
"I'm very encouraged with the support we have received from the public and immediately calling them in, that we stand a strong chance" of eradicating the invasive hornets, he said. "I'm cautiously optimistic that we will reach that goal."
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