Bugging Out

“Murder hornets" explained: Their scariest threat is not their venomous sting

Everyone is bugging out about a nasty, giant hornet — but the ecosystem has the most to worry about.

A species of insect previously unseen in the United States is here — and it's big, fast, and deadly. Meet the Asian giant hornet, now popularly known as the "murder hornet."

This week a New York Times article on their emergence in Washington state caused the news of their arrival to go viral. But while jokes online trend toward "first comes a pandemic then comes 'murder hornets,'" the Washington State Department of Agriculture (WSDA) actually announced in February that four reports of Asian giant hornets near the cities of Blaine and Bellingham were verified in December.

The massive insects — native to a wide swath of East, South, and Southeast Asia, and East Russia — appeared in North America even earlier than that. While the December emergence was the first time Asian giant hornets were seen in the US, they were seen in two locations in near-by British Columbia in the fall of 2019, the WSDA reports.

While these insects have the ability to cause harm — in Japan, they kill up to 50 people a year — their greatest threat to humans is not their sting. Instead, it's their proclivity for killing other insects — insects that we very much need to keep alive because of their effects on the ecosystem and agriculture.

Meet the "murder hornet" — True to its moniker, this hornet's potent, venomous sting can be deadly to humans – especially if a person gets stung multiple times. While they are not the only deadly hornet, these bugs pack a particular punch. Their sting contains a specific neurotoxin that can sometimes send people into anaphylactic shock.

An Asian giant hornet found in Japan.

However, the number of people who actually die because of these stings is low even in areas where they have established populations. In Japan, the giant hornet kills between 30 and 50 people per year, according to a 2006 Clinical Toxicology study.

Still, the insect is formidable. Its orange-and-black striped body is around 1.8 inches long, with a 3-inch wingspan. This makes it the biggest known wasp (hornets are a type of wasp).

The giant hornet is also the fastest wasp in the world, clocking in at up to 25 miles per hour.

Why is it called a "murder hornet"?

If you ask most entomologists, they would say that it is not.

The New York Times cites an explanation from Kyoto Sangyo University researcher Jun-ichi Takahashi, who says that these insects earned their "murder hornet" nickname because of their aggressive attacks and fatal stings.

However, Michael Skvarla, an assistant research professor of arthropod identification at Penn State, writes that there is no accepted common name for these hornets in English. They are technically named Vespa mandarinia, and are known as "great sparrow bees" in Japan, "tiger head bees" in China, and "general officer hornets" in Korea.

"As far as any entomologist in the United States can tell, 'murder hornet' was not used in English prior to the NY Times article," Skvarla explains. "Therefore, it is not recommended to refer to V. mandarinia as 'murder hornets.'"

A male Vespa mandarinia.

Who should actually watch out for these hornets? — Bees.

Terrifying as this new-to-the-states species might sound, only a few of these hornets have shown up so far and they don't tend to go after humans. People tend to come into harm's way only when they disturb a nest, which is usually located in a burrow underground.

If the giant hornet continues to spread in the United States, the creatures most likely to suffer will be local insect populations — and, indirectly, the humans that rely on them.

Giant hornets feed on other insects, including bees, whose populations are already struggling in the face of pesticides, climate change, and ecosystem disruption.

For honeybees, the consequences of coming into contact with a giant hornet can be dire.

A single Asian giant hornet can kill a hundred honeybees in hours — meaning a handful of the hornets can destroy an entire colony. In fact, it was a ravaged hive that tipped off beekeeper Ted McFall to the notion that the "murder hornets' had infiltrated Washington.

The giant hornets first lop off the smaller bees' heads with powerful mandibles. Then, after decapitating the worker bees, the giant hornets will begin to eat the honeybees and their larvae, saving some of the meal to feed to their own young (after first chewing the prey into goop).

Luckily for Japanese honeybees, they've developed a way to fight back. They swarm around the giant hornets, forming a ball of bees that heats up as hot as 115 degrees Fahrenheit. This bee ball literally cooks the giant hornet.

Researchers described the phenomenon of a “hot defensive bee ball” in a 2012 study published in the journal PLOS ONE.

(A) Presentation of a wire-hung hornet to the beehive as a decoy. (B) Hundreds of workers form a hot defensive bee ball surrounding the wire-hung giant hornet. (C) Bee ball recovered in a glass beaker. (D) The giant hornet is dead 60 min after the bee ball forms.

Ugajin et. al, PLOS ONE, 2012

Unfortunately, European honeybees — which have populated the United States since the seventeenth century — have not developed a similar defense. That may prove to be a problem because pollinators like honeybees are already at major risk in North America.

Bee populations have declined dramatically in recent years: From 2018 to 2019, 40 percent of bees under keepers' care in the US disappeared.

Since pollinators like bees and butterflies are directly responsible for one-third of the food we eat, preserving pollinator biodiversity may be key to feeding the world's growing population.

Hunting for hornets — Researchers aren't exactly sure how these hornets arrived in the US, but it's possible they hitched a ride in a shipping container, National Geographic reports.

As a result of the news, more people seem to be on the lookout for giant hornets. Entomologist Matt Bertone posted a slew of insect identification requests on Twitter. Peeking at the influx of requests in Bertone's inbox, most of them seem to be related to the Asian giant hornet. This, crucially, doesn't mean they are actually seeing the hornet in their homes.

Unfortunately, fear of these insects seems to be driving people to kill bees and wasps that aren't Vespa mandarinia, according to Eric Lee-Mäder, co-director of the pollinator program at the Xerces Society, a conservation group.

"We see people mistaking newly emerging bumblebee queens... mistaking those as the Asian giant hornet and unfortunately, in some cases, even killing those bumblebee queens," Lee-Mäder told KWG8 News.

There is no need for people to panic over these insects, Lee-Mäder says. However, he does say they pose a risk to local insects.

"We have no idea what this means for native wild insects," Lee-Mäder said. "For our native butterflies, for our bumblebees. I think that's the bigger question."

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