First U.S. "murder hornet" nest found near B.C. border in Blaine, Washington

The first U.S. nest of the invasive Asian giant hornet has been found in Blaine, Washington, and authorities there plan to destroy it immediately, along with all its occupants.

The discovery announcement came at a virtual news conference called by the Washington State Department of Agriculture (WSDA) today (October 23).

A nest uncovered in Nanaimo, B.C., on Vancouver Island in August of 2019 was the first to be found in North America and was quickly destroyed. It is thought that those hornets originated from a foreign ship that anchored at one of the port's two deep-sea terminals.

A single giant hornet found in White Rock in November 2019—and the sighting of two of the giants near Blaine the next month—led to information campaigns and searches by government officials on both sides of the international border.

In Washington state, government researchers and so-called citizen scientists and other volunteers set hundreds of traps in Whatcom County. In B.C., government information bulletins went out to residents along the border, and more traps were deployed.

"The nest is inside the cavity of a tree located on private property near an area cleared for a residential home," the WSDA said in a news bulletin released simultaneously with the virtual announcement. "While Asian giant hornets normally nest in the ground, they are occasionally found nesting in dead trees. Dozens of the hornets were seen entering and exiting the tree while the WSDA team was present.
 
"The property owner has already provided permission for WSDA staff to eradicate the nest and remove the tree, if necessary."

The Asian giant hornet (scientific name Vespa mandarinia) is especially feared by agricultural experts, farmers, and beekeepers because of its propensity (especially in the fall, prior to breeding and the queens' winter hibernation) to annihilate honeybee hives in a matter of hours, cutting up their inhabitants with large mandibles and carrying their larvae and pupae back as food for themselves and their young.

WSDA managing entomologist Sven Spichiger explained the invasive insect's seasonal belligerance to the Seattle Times on October 2: "Asian giant hornets this time of year start going into what we call the slaughter phase. They will visit apiaries, basically mark a hive, attack it in force, removing every bee from the hive, decapitating them, killing all of the workers, and then spending the next few days harvesting the brood and the pupae out of the hive as a food source."

Honeybees are responsible for pollinating up to a third of food crops, and many North American fruit, vegetable, and nut crops would disappear without them. Their populations in Canada and the U.S. had declined by as much as 50 percent during the past few decades—the losses attributed, variously, to pesticides, habitat loss, climate change, disease, and parasites—but their numbers have been increasing in recent years.

The giant hornet, the world's largest, is relatively common in East Asia, including Japan, Korea, and parts of China, and it has spread to Malaysia, India, and Tibet.

It has been blamed for hundreds of human deaths over the years, and Chinese officials in 2013 said an alleged spate of attacks in and around Shaanxi Province killed 42 people and injured about 1,600 during a three-month period. 

Japanese studies show that 30 to 50 people die every year in that country as a result of giant-hornet stings. The U.S. Centers for Disease Control and Prevention has estimated that about 62 people die every year from bee and wasp stings in the U.S.

At the virtual news conference, WSDA entomologist Spichiger announced the nest discovery, made in the late afternoon the previous day (October 22), on the Blaine property.

In the same-day release, the WSDA said two live Asian giant hornets were found in agency traps on October 21. The insects are sometimes called "murder hornets" because of their size (up to 5.5 centimetres in length), the ability of only a dozen or so to kill as many as 30,000 honeybees in a hive in only a few hours, and the fact that their stings sometimes kill humans.

When entomologists returned the next day to attach miniature radio transmitters to the hornets to track them back to their nest, according to the release, they found two more live hornets trapped.

After attaching transmitters to three of the hornets, the trappers were able to track them to the property in Blaine.

“And at that point,” Spichiger said during the virtual news conference, “I actually heard a hornet buzz over my head, so we assumed she had left the location. But then we heard another one buzz over my head, and I took a step back and realized we were actually standing right under the nest. We had in fact tracked her straight back to where she came from. And so we were pretty happy about that."

Due to the late hour, the release said, it was decided to destroy the nest the next day, but "inclement weather" today meant that officials would carry out those plans Saturday (October 24).

Asian giant hornets are not hostile toward humans if left alone, but they do become agitated and will often attack animals and people if they feel that their nest is threatened. It is often difficult to know if a nest is nearby due to the hornets' habit of sometimes contructing them underground or in tree cavities.

The expansion of farmlands and populous urban areas in China, Japan, and other countries has led to increased human encounters with this largest member of the wasp family. In China, the Asian giant hornet's breeding season is in the fall, immediately prior to which it becomes increasingly fixated on gathering protein and is more aggressive and potentially dangerous to humans.

Giant hornet venom is especially potent, killing red blood cells and sometimes even requiring hospital stays and kidney dialysis for their human victims. In China, stings have been known to require stitches and sometimes have resulted in open wounds that resemble bullet holes, according to Chinese and Japanese researchers. These symptoms, along with a rare multiple-organ-failure outcome, usually present in people who have been stung dozens of times.

Those most at risk of potentially deadly reaction to the stings are people who are severely allergic to insect venom and are in danger of developing anaphylactic shock, which can cause cardiac arrest or close airways through tissue swelling.

If you spot what you think may be an Asian giant hornet, the Invasive Species Council of B.C. asks that you call them at 1-888-933-3722 to make a report (or you can complete an online form here).