Scientists Destroyed a Nest of Murder Hornets. Here’s What They Learned.

Asian giant hornets — better known as murder hornets — inspired menacing headlines throughout the summer amid warnings that the invasive insects could decimate American honeybee populations. Last month, after various sightings across the Pacific Northwest, officials in Washington State discovered and removed the first known murder hornet nest in the United States.

As officials continue to seek out other nests for destruction in hopes of eradicating the hornets from the country, entomologists are revealing what they have learned from the first nest removal.

“It really seems like we got there in the nick of time,” Sven-Erik Spichiger, managing entomologist at the Washington State Department of Agriculture, said at a news conference about the nest’s findings this week.

Here’s what the scientists have discovered.

Late last month, officials in Blaine, Wash., removed the nest of aggressive hornets — which were about to enter their “slaughter phase” — before they could multiply and kill the area’s honeybees. Had they not been removed, the insects could have laid waste to the pollinators vital to the region’s raspberries, blueberries and other crops.

The hornet is not native to the United States and can be more commonly found in Asia, where it has been known to kill up to 50 people a year in Japan.

The Blaine colony was located in a region of forests and farmland after officials attached radio trackers to three hornets that they had trapped earlier. One of those hornets led officials to the nest, which was about eight feet up in a tree.

Entomologists extracted a few hundred hornets with a vacuum and then sealed the rest of the nest shut on Oct. 24, Mr. Spichiger said at the news conference, held virtually on Tuesday. Officials later removed the section of the tree where the nest had been sealed and took it to a quarantine research center at Washington State University.

On Oct. 29, officials opened the nest to find most of the insects still alive. Including the hornets that were vacuumed up days before, officials said they removed about 500 hornets in various life stages from the nest, which was about 14 inches long and at least eight inches wide.

In addition to the 112 worker hornets that were found, there were hundreds of larvae and pupae (the life stage after larvae), as well as some eggs and male hornets. Mr. Spichiger also said the nest was capable of holding about 200 queens.

The nest is smaller than those found in areas to which the hornets are native, where there can be as many as 700 queens, Mr. Spichiger said.

Although Mr. Spichiger said officials removed many of the queens from the nest just in time, he said there were some that could have escaped and could form new colonies next year.

At least three queens were found in a nearby water bucket after the extraction, he said, adding that it was impossible for officials to be certain that they had caught all of the hornets or of how many more there could be.

“When you see all the relatively small nests able to pop out 200 queens, it does give one a little bit of pause, because eventually each of those queens could be a new nest,” he said.

If any queens escaped, they might not survive if they had not received adequate nutrition before leaving the nest. But if one was properly fed and had mated with a male, she could theoretically go off and pick a protected area to be insulated through the winter, helping to form new colonies in the spring.

“It’s clear since we captured specimens last year and captured queens early on that a few of them did manage to establish nests in 2020,” he said.

Hoping to eventually eradicate the hornets, State Agriculture Department workers will continue trapping them until at least Thanksgiving.

However, officials will not track any queens they may capture because they are not likely to return to a nest for officials to eradicate. At this point in the season, officials’ best chance of locating another nest is if the hornets go on to attack a beehive, Mr. Spichiger said.

The discoveries from this nest have left officials unsure of how the hornets got to the Pacific Northwest in the first place. Mr. Spichiger said it was likely that a mated queen made its way to Washington through international trade. He also said it was possible that someone had smuggled the hornets into the United States to raise them as food. (They are sometimes eaten as snacks or used as an ingredient in alcoholic drinks.)

Even if there are no other hornets found in the area in the future, officials will continue to use traps for at least three more years to ensure that the area is free of the hornets.

“These are not going to hunt you down and murder you,” Mr. Spichiger said. But, “If you walk into a nest, your life is probably in danger.”

Still, he added, “your life is also in danger if you walk into the nest of other stinging insects as well.”


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