Hornet Hunt

Scientists and local beekeepers are on the lookout for an invasive hornet in Washington State that poses a threat to local honeybee populations.

Story by Alex Crump

December 11, 2020

The Asian giant hornet (Vespa Mandarinia), the largest hornet in the world, has gained a foothold in the United States for the first time. Almost as large as an adult human’s thumb, with a bright orange-yellow head and a chilling buzz, the deadly hornet has arrived in the Pacific Northwest and may not leave without a fight.

Scientists don’t yet know how the hornets will adapt to survive in this climate, but they have already begun to wreak havoc. In November 2019, local beekeeper Ted McFall was devastated to see one of his honeybee colonies completely destroyed. While he was uncertain at first as to what could have happened, the beekeeper soon came to suspect the Asian giant hornet was the culprit.

“At that point in time, we didn’t know. I mean, nobody knew much about the Asian giant hornet,” said Ruthie Danielsen, a local beekeeper who caught the first worker hornet alive in the United States.

It’s still unclear exactly how or when the hornets arrived in Washington State. Scientists agree that doesn’t matter now. Focus has shifted to coping with the invasion.

“Our overall long-term goal would be to hopefully eradicate the Asian giant hornet,” said Karla Salp, spokesperson for the Washington State Department of Agriculture (WSDA). “[Our] short-term immediate goal is to determine the extent of the spread of Asian giant hornet in Washington State, and that’s going very well.”

After reports of the initial attack, the WSDA took the lead on trapping, tracking and finding the hornets’ nests. Local citizens, hobbyist beekeepers and state officials have placed thousands of traps. These include bottle traps, small bottles partially filled with a mix of rice wine and orange juice. These have been used to catch these hornets for years in Asian countries where they are native, according to Danielsen.

The promise of a sweet treat lures the hornets in. Unable to escape, they eventually drown in the mixture. Live traps are similar, but instead have a small grate inside that prevents the hornet from drowning — a live hornet is much more valuable to scientists than a dead one.

This year, entomologists and citizen scientists — local volunteers who make traps and monitor them on a daily or weekly basis — focused efforts on trapping hornets so the WSDA can place trackers on them to find more nests.

Despite the widespread effort, scientists are still pressing to learn more.

Tim Lawrence, an associate professor at Washington State University who has nearly 60 years’ experience in “all aspects of honeybee,” provided the region with a handful of sentinel colonies. The sentinel hives essentially act as hornet bait and are equipped with a net-like barrier. The holes in the net are just wide enough to allow honeybees in and out, but any giant hornet that tries to enter will become stuck.

“Do not call it the murder hornet,” Lawrence said, wanting to dispel certain speculations about the hornets.

Whatever they are called, the hornets can be lethal to other insects. Starting in the late summer, the hornets begin the queen-rearing process and reach what entomologists call the “slaughter phase,” when they begin attacking hives of bees and wasps.

Foraging hornets will swarm a beehive, releasing pheromones to summon more hornets as backup. A few hornets can destroy an entire beehive population in a matter of hours.

A couple then stay to patrol the occupied beehive, ready to attack any creature that gets too close, be it a honeybee or a human. This is when the hornets are most volatile. After decapitating the bees inside, the hornets chew up larvae and return the baby bee paste to their nest as food. It’s important for the hornets to protect the precious cargo. The goop is full of proteins and carbohydrates, which the hornets need to produce their own larvae, an army of workers, drones and most importantly, queens.

One hive can produce upwards of 300 queens, according to Danielsen. It’s not clear how many of them will go on to form colonies and the rate of survival is very low, said Sven-Erik Spichiger, managing entomologist at WSDA. Around the start of a new year, a mated queen begins to hunt for a small place to take shelter and lay her eggs for the cold months. At this point, hives usually die out, although sometimes they can survive the winter and return the following season. Only the queens that received enough nutrients from the bee larvae mash are likely to survive the winter, and only the ones that mated before the new year are likely to form a colony of their own, so just a small percentage have the potential to reproduce in a given year.

The queens that survive the overwintering process, along with their larvae, will emerge in the spring and begin building a more permanent nest, usually underground, where the cycle begins again.

The hornets can be dangerous. In Japan, they kill between 25 and 50 people per year, according to Spichiger. Just one of the extraordinarily painful stings can kill people that have bee allergies. Hornets also release pheromones to mark a target, signaling all the hornets in the area to attack; and hornets, unlike bees, can sting multiple times. Tissue death and intense swelling can happen around the site of the sting, and in rare cases humans can suffer organ failure or go into anaphylactic shock.

As if the stings weren’t terrifying enough, the hornets also spray venom out of their mouths, something WSDA scientists learned the hard way. They now wear eye protection when dealing with them.

The best thing to do when coming face-to-face with these hornets is to steer clear. When in close contact with a hornet, people should back out of the area and report the sighting to WSDA. The department uses the data to triangulate possible locations where a nest could be located.

Outside of being a nuisance to people and a threat to honeybees, the Asian giant hornet could hurt Whatcom County’s economy.

Whatcom County produces 85% of the nation’s red raspberries, according to Whatcom Conservation District. Many berry farms rely on honeybees, both migratory and non-migratory, for pollination. The berry industry’s reliance on honeybees, combined with a new invasive predator, could cause trouble, according to Lawrence.

However, berry pollination occurs in the summer, while the hornets do not enter their slaughter phase until the fall. This creates a window of opportunity for migratory beekeepers to get in, pollinate the berry bushes and leave before the hornets begin seeking out honeybee colonies to destroy.

The hornets are viewed as a delicacy in Japan, and some theorize they could have been brought to the U.S. for similar reasons. One popular cultural tradition is to steep live hornets in a strong liquor, called shochu. As the hornet dies, they release their venom into the liquor, turning the clear spirit bright amber, as if it’s been aged in an oak barrel. When consumed, the venomous cocktail can give the drinker a numbing sensation as well as a decent buzz.

In October 2020, WSDA scientists launched an operation to remove the first nest found in the United States, just outside Blaine, Washington. They had successfully tracked a hornet back to the nest with a radio tag. Asian giant hornet nests are usually in the ground, but this one was found about eight feet high in a dead alder tree.

The scientists arrived at the scene in hornet-proof suits thick enough to stop the hornets’ half-centimeter long stingers. The suits resemble a cross between a spacesuit and a giant marshmallow, but they help to provide protection from the hornets. Once the tree was cut down and the nest removed, scientists went to work examining its contents. In total, the nest contained about 500 hornets at various stages of their life cycle, including 200 queens, according to Spichiger.

The hornets have survived one Washington winter and look poised to live through several more, though scientists at WSDA remain confident in their ability to contain their spread.

“Right now, it still looks cautiously optimistic that we are still kind of ahead of this,” Spichiger said. Three years must pass without a sighting or report before scientists can declare the threat eradicated.

The Asian giant hornet is here, at least for now. Fortunately, their foothold seems limited to just Whatcom County.

“If I had told you we had 17 different hits in 17 counties, I’d say the genie was out of the bottle,” Spichiger said during a November press conference. “But right now it’s just [Whatcom County] and British Columbia, and it’s a fairly contained event.”

Alex Crump is an environmental studies major in his fifth and final year at Western. This is his first contribution to The Planet.