Murder Hornets Could Spread Across U.S. and Establish Permanent Presence, Experts Say

Asian giant hornets have the potential to spread across the United States and establish a permanent presence in the country, experts have told Newsweek.

The hornet species—the world's largest—is native to eastern and southern portions of Asia, however, the insect was detected in British Columbia, Canada in September 2019, and subsequently, across the border in a single county of Washington state in December of that year.

"I suspect if they are not stopped in Washington they will spread across the more temperate regions of the United States—basically, any place that approximates where they are already established, and, as they are closely related to our paper wasps, probably where those are established too," Marc Lame, clinical associate professor at Indiana University's O'Neill School of Public and Environmental Affairs, told Newsweek.

"If they do establish and do not encounter indigenous natural enemies they probably will become permanent. Very few invasive insects have ever been successfully eradicated once they have established. Much depends on a successful, coordinated and well funded government surge at this time. Even then, I am pessimistic," he said.

Allen Gibbs, an insect expert from the School of Life Sciences at the University of Nevada, Las Vegas, also told Newsweek that the Asian giant hornets (Vespa mandarinia)—sometimes referred to as "murder hornets"—could become "very widespread" in North America as an invasive species.

"They could become a permanent feature if they aren't wiped out soon," Gibbs said. "An apparent queen was found this spring, suggesting that she may have overwintered and founded a colony. And an active colony was found and destroyed in Canada last year."

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However, another expert, David Ragsdale—professor in the Department of Entomology at Texas A&M University and member of the college's Murder Hornet Task Force—said that despite the potential for the insects to establish and spread, it is still too early to tell whether or not this will be the case.

He told Newsweek that the United States Department of Agriculture and the Animal and Plant Health Inspection Service's Plant Protection and Quarantine program are currently doing all they can to eliminate the invasive insect before it gets a foothold.

Nevertheless, the hornets have survived one winter in northwest Washington state and, thus, could likely adapt to other areas further south, Ragsdale said.

"Their ability to move on their own is somewhat limited—probably on the order of a few miles per year. But they are very willing to hitch a ride in a truck, and this is how they will likely move larger distances," he said.

"They did make it from Japan to British Columbia—likely using a container ship as the means of conveyance, but other methods, including intentional transport by people, is also possible. In Japan, the larvae of the Asian giant hornet are consumed as a delicacy."

Other researchers, such as entomologist Brian Lovett from West Virginia University, are less confident that the hornets will spread across the country.

"In my view, it is unlikely that this pest will become widespread in the United States," he told Newsweek. "Entomologists are already working hard to eradicate it, and because of how it develops, there is a window where workers can be detected before new queens are produced in mid-September."

"New queens are the avenue of expansion for this hornet. The public is now well aware of a very large hornet, so it would be difficult for the Asian giant hornet to fly under the radar. Due to these factors, it's unlikely these hornets will travel beyond the Pacific Northwest."

Currently, there does not appear to be a widespread invasion of the hornets, and researchers hope that there are relatively few colonies, or even a single colony, according to James Nieh, a scientist at the University of California San Diego's Division of Biological Sciences.

Asian giant hornet
Washington State Department of Agriculture entomologist Chris Looney displays a dead Asian giant hornet, a sample sent from Japan and brought in for research, on May 7, 2020, in Blaine, Washington. ELAINE THOMPSON/POOL/AFP via Getty Images

"Note that these are social insects and can only reproduce within a colony. Thus, the key is to eliminate established colonies," he told Newsweek.

Lovett is optimistic that the giant hornets in the U.S. can be controlled, especially after a new individual was trapped in Washington state recently.

"Part of the reason a new individual was trapped was because entomologists in Washington state are carefully monitoring the local insect community with traps," he said. "These entomologists have also put a call out to the Washington community to report any possible sightings so they can zero in on possible Asian giant hornet colonies."

"Once the colonies are discovered, there are straightforward means to eliminate them using insecticides or simply smothering the colony with carbon dioxide. It is absolutely not too late to eliminate these insects from the United States, and I have faith that the entomologists and community members in Washington state will take all necessary action to keep this potentially invasive insect contained."

Despite their nickname, Asian giant hornets—which can grow up to two inches in length—pose little risk to humans. People who come across a colony could face being stung, which is painful—although for the small portion of the population who are strongly allergic to bee stings, this could have serious health consequences.

"For that small portion, the Asian giant hornet poses an increased threat because of its size, and the fact that it can inject about seven times the volume of venom of a bee or wasp," Ragsdale said.

In Japan, where the hornet is native, around 30-50 die every year as a result of their stings, although this figure is similar to the roughly 60 people who are killed every year in the U.S. by bee stings.

But experts say that, if the hornets were to become established in the United States, the biggest threat they pose is to honeybees. In the U.S., European honeybees are used to produce honey and, more importantly, pollinate crops. Many vegetable and fruit crops are dependent upon insect pollination, and honeybees are the most common pollinators of these crops.

However, honeybees have no innate defense against the Asian giant hornet, which are specialized predators of these key pollinators.

"Economically, beekeepers should be especially worried; the hornets can wipe out a hive in an hour or two," Gibbs said. "Honeybees are already facing many problems; these hornets would just add more stress to them. If honeybees are significantly affected, bee-pollinated crops would suffer."

But according to Lovett, we are very far from this being a meaningful concern for beekeepers in the U.S.

The hornets could possibly also attack native social insects, such as bumblebees, which play an important role in ecosystems, according to Nieh.

Lovett said that the ecological risk posed by what may be a single colony of Asian giant hornets in northwestern Washington is currently "very low."

"I would argue that the biggest ecological risk posed by these hornets currently is the fear the sensationalized stories have instilled in people. People, driven by fear of the 'murder' hornet, will try to trap and kill local wasps," he said. "Indeed, many entomologists I know have been sent pictures of dead wasps which turned out to be usual members of our ecosystem."

"These hornets are predators of insects, not people, and would only sting us if they are territorial (near nests) or provoked. These innocent victims of 'murder hornet panic' are beneficial members of our community and their loss has likely done more harm to North American ecosystems than the mandibles of any Asian giant hornet," he said.

This article was updated to include additional comments from Brian Lovett.

Murder Hornets Could Spread Across U.S. and Establish Permanent Presence, Experts Say | Tech & Science