Photograph Courtesy Washington State Department of Agriculture
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Asian giant hornets, the world's largest wasp, have been spotted in Washington State, and researchers are trying to eradicate the invasive species.

Photograph Courtesy Washington State Department of Agriculture

Another ‘murder hornet’ found in Washington State—here’s what that means.

The discovery of a third Asian giant hornet suggests the species has survived the winter and spread—but it’s not too late to stop it, experts say.

An Asian giant hornet that’s almost certainly a queen was discovered in Washington State, scientists have confirmed, the third found in the United States. But officials stressed that the sightings have been confined to a relatively small area in the northwest corner of the state, and that there’s a chance to stop the insect’s spread.

The discovery likely means a colony was present near Custer, Washington, in fall 2019, and that it produced many queens.

These large females lie dormant over the winter, and when they become active in the late spring, a small percentage are likely to create successful nests.

A man walking on a road near Custer noticed the dead insect last week. It was the first hornet seen this year, following the confirmation of two individuals in December. (The nest that produced those hornets, including its queen, would’ve died out by now.)

The finding adds urgency to ongoing efforts to trap and track the hornets, said Sven Spichiger, an entomologist with the Washington State Department of Agriculture, in a news conference Friday.

“Since colonies can produce hundreds of queens, we probably have a few more to find,” Spichiger said of the insects, which have been trending recently on social media as “murder hornets.”

“It’s disappointing to know they can make it through the winter and survive here, but it doesn’t change what we plan to do—we have a [good] chance to eradicate them,” he added.

Entomologists don't use the term “murder hornet,” which Japanese researcher Junichi Takahashi coined to reflect the insect's aggressive hunting of bees. Spichiger says he greatly dislikes the term, and is concerned that some coverage of the insects has amounted to “unnecessary sensationalizing.”

Environmentalists and scientists say that unfounded fears about the hornet have sparked a recent surge in internet searches for insecticides. The term "how to kill hornets" and similar iterations have spiked on Google since early May, when the insects hit the news. Indiscriminate spraying could harm several smaller, more benign species of hornets that are native to the United States and are vital pollinators for many plants, including valuable agricultural crops.

Spichiger stressed that aside from a small area of northwestern Washington, no one in the U.S. needs to worry about Asian giant hornets.

On the hunt

Researchers hope to trap any Asian giant hornets in the area where the putative queen was found using a mixture of fruit juice and rice wine. They'll then outfit the insects with tracking devices, which should reveal the location of their colonies, Chris Looney, an entomologist at the Washington State Department of Agriculture, said in an email interview. Those colonies will then be destroyed.

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An Asian giant hornet discovered May 27 on a road near Custer, Washington. The specimen was almost certainly a queen that survived the winter.

In early summer, fertilized queens that survive the winter begin laying eggs, which hatch into workers. Nests can have hundreds of workers, which supply the queen and colony with food.

If the nest is successful, by fall it will have produced many new queens and males that will breed and disperse, to start the cycle anew in the following year. The workers and the queen in the original colony will die.

The “murder hornet” nickname comes from how viciously hornets prey upon honeybees. Asian giant hornets can destroy an entire bee colony in 90 minutes by decapitating the workers and feasting on the larvae.

That’s one reason that people are so worried about Asian giant hornets—but the insects also have very painful stings, which can occasionally be fatal. The animals cause between 30 to 50 deaths per year in Japan alone, but most of the fatalities are due to allergic anaphylactic reactions rather than acute toxicity. (Learn more: Why Asian giant hornet venom is so intense.)

Mysterious queens

In mid-May, another Asian giant hornet was found in Langley, British Columbia, around 10 miles north of Custer. Genetic tests have revealed that hornets in Canada and the United States arose from different importations, almost certainly in shipping containers from Asia.

Until the recent finding near Custer, scientists had hoped that the workers found in December could have come from a colony that didn’t succeed in producing new queens—a hope that is now dashed. But at the same time, they knew it was likely.

Citing studies from Asia, Looney says that as few as 30 percent of hornet queens successfully mate. A much smaller percentage will survive long enough to lay eggs and establish a successful colony with workers, he adds. Tests will soon show if the queen found on the road was fertilized, Spichiger says.

Before establishing colonies, these newly emerged queens likely will fly around a bit, feeding. Beyond that, most of their behaviors are still very much a mystery, Looney says.

It's “a major knowledge gap—I would argue one of the most significant—for planning our survey efforts,” he says. “We do not know how far they fly, what conditions determine flight range, if there are multiple flight events... We simply do not know.”