Jul 7th 2021
No one knows how the queen first arrived in Washington state. The most likely explanation is that she found a cosy spot to spend the winter, perhaps among some cargo that was later ferried first to a commercial port in East Asia, and then across the ocean by ship. When she reached a new shore she would have been awoken, maybe by the foghorns of tugboats, by the deep thump of cranes stacking containers or the screech of gulls cutting across the grey sky. Her muscular wings carried her through the cold air as she set off to find a cosy place to nest and lay her eggs, ignorant of the significance of her arrival and the terror she would sow.
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In May 2020 this unsuspecting creature was christened the “murder hornet” by the New York Times. The story about killer insects briefly gripped the nation, the name an apparent reference to the hornet’s propensity to slaughter entire hives of honeybees. A single Japanese entomologist was cited as the source of that label – in Japan the hornet is known as the osuzumebachi, the giant sparrow bee. Its English name is less lurid: the Asian giant hornet.
The hornet’s arrival in north-western America was first announced in December 2019. Six months later, in May 2020, the threat of “murder hornets” went viral. In that time the world changed: two-week lockdowns slipped into months of isolation and grief. Death tolls ticked up on our screens. “It felt like everything was getting worse,” said Justin Bush, who works for the Washington Invasive Species Council, a government environmental body. Murder hornets – foreign agents of chaos spreading unseen to continental America – seemed like the perfect avatar for this apocalyptic year.
Troublemakers in Washington caused panic by putting up signs in nature reserves: “Stay Alert: Murder Hornets Decapitate People”. They do no such thing. Yet so many petrified locals called the emergency services that the Washington State Department of Agriculture trained operators to pacify callers who’d supposedly made a sighting. One lookalike, the native bald-faced hornet, was stabbed with a hunting knife on the desk of a Washington courthouse.
This story about killer insects briefly gripped the nation
The biggest misconception about the hornet is easily debunked: it isn’t particularly dangerous to humans. Wasps, bees and hornets kill roughly 20 people a year in Japan (America’s population is nearly three times that of Japan, and at least 90 die from stinging insects each year).
The scant few who do die have an allergic reaction to the venom. One man in Vietnam was vigorously agitating a nest while hunting hornetlarvae, with no protective equipment, and didn’t flee when insects began stinging. “If he had only been stung 30 times all over his body, he’d probably still be here,” said Chris Looney, an entomologist at Washington’s agriculture department. “But he was stung 80 times on the head. That’s an exceptional case.” By contrast, a nest found in Canada in 2019 lay only feet away from a popular trail. No passersby were stung. “They’re uninterested in attacking you unless you give them reason to,” said Looney.
The harm they pose is to America’s honeybees, themselves once immigrants from Europe. The hornets target bees during the “slaughter phase” of their development, as scientists call it, which is as gory as it sounds. After a peaceful summer carb-loading on tree sap, a hornet scout leaves the nest to find protein in the form of a beehive full of larvae. The hornet secretes a pheromone from a gland in its abdomen and smears this over the hive, which spells death for the bees within. The scout will return with a killing squad of between two and 50 hornets the size of hummingbirds. Each one has jaws that can decapitate a bee in a single bite.
As the bees emerge to defend their home, the hornets systematically behead them until the hive is bare. Six hornets can dispatch a thriving hive in under two hours. Then the hornets pillage the hive for the protein-packed larvae – their real quarry – and carry it back to their own swarm. The beheaded bees are left in a pile at the hive’s doorstep.
This carnage matters even if you aren’t an insect lover. The Asian giant hornet may not threaten humans directly, but it does so indirectly because bees play a central role in our lives: bees help pollinate one in every three mouthfuls of food people eat in America, from apples and peaches to almonds and canola. Some $15bn-worth of crops a year in America are pollinated by bees, according to the United States Department of Agriculture.
Murder hornets – foreign agents of chaos spreading unseen to continental America – seemed like the perfect avatar for this apocalyptic year
In Asia, honeybees evolved alongside the hornet. The insects have learned to co-exist as, over millennia, Asian honeybees have built defences against the hornet: they can smell the pheromone that marks their hives for destruction and clean off the chemical. The bees have also learned to swarm the hornetscout, beating their wings so fast that they generate heat and carbon dioxide which suffocate their predator. American honeybees, by contrast, are entirely defenceless.
Ted McFall is a third-generation beekeeper, softly spoken with a slight southern wheeze, who spent years qualifying to become a master beekeeper. Five years ago he decided it was time for a new adventure, and moved his apiary from the southern tip of Texas to the northernmost corner of Washington state. Like most beekeepers, McFall makes his money less from honey than by pimping out his bees to farmers for their pollination services.
A silent killer An Asian giant hornet (opener). Checking traps for the Asian giant hornet trap in Washington state (top, middle and bottom)
At 42 he has weathered a number of severe threats to his swarm. Sometime in the 1980s Varroa destructor, a parasitic mite, arrived in America from Asia. This feeds on honeybee pupae as they develop, and then compounds the destruction by bringing pathogens into the hive. Its spread was slow but destructive. It is one of many possible causes for a phenomenon known as colony-collapse disorder, the unexplained deterioration in the health of hives, which many beekeepers have noticed since the mid-2000s.
Intensive farming poses an ongoing threat to bees, too, as weed-killers and monocultures make it hard for insects to eat a varied enough diet (often including weeds): they need sufficient nutrients to boost their immunity against diseases and parasites such as the Varroa mites. If crops are sprayed while they’re flowering, as sometimes happens, bees will also eat a lot of pesticide. Even without the arrival of a new predator, the average beekeeper loses some 40% of their hives each year.
But in November 2019 a catastrophe came out of nowhere: McFall lost his most productive hive overnight. It was the first and so far the only hive in America known to have been annihilated by Asian giant hornets. “Losing your best hive is like killing a winning racehorse,” McFall said. He had planned to use Ginger, the hive’s queen, to breed more queens and establish additional hives.
The massacre was both distressing and confusing, since no one knew about the Asian giant hornet’s arrival. “Not knowing what caused their deaths, not being able to do anything about it, it was the most helpless feeling I have ever had,” McFall told me. He took pictures along to the Mt Baker Beekeepers Association, which holds monthly meetings for “people who like to share their love of bees”. The group were horrified by photos showing a heap of tiny headless bodies at the entrance to a hive.
Signs in nature reserves read: “Stay Alert: Murder Hornets Decapitate People”
McFall’s apiary lies on the edge of an organic livestock farm ringed by a forest. Mist hung in the cold air and farmworkers were rolling their children inside tractor tyres when we pulled up in McFall’s black truck.People waved as McFall shoved fabric into a bee smoker – an oil can with bellows, which pumps smoke into the hives to calm down the bees – and set it alight. “Don’t bow your head,” he said as I donned a beekeeping suit. “The only way they can get you is when the mesh face-covering touches your skin.”
He asked me to pump the bellows as we walked over to his remaining bee boxes. We stood on the precipice of winter and the bees were agitated as they sought to protect their honey, their source of food for the months ahead. Three pumps of smoke stupefied them.
McFall has grown accustomed to being interviewed over the past year: he is the only person in America to lose a hive to the Asian giant hornet, and his loss is still raw.
“This is Wuhan,” he said, eyes brimming with fury that looked almost like glee.
For thousands of years, we have tampered with the environment in which we live. Humans have domesticated animals and plants, and pillaged the Earth for natural resources. The scale of our intervention, combined with industrialisation and globalisation, means that the effects of our actions are no longer limited to places in which they occurred. Coal burned in northern Europe results in ice melting on the other side of the world.
We talk of invasive species, those which are not native to a habitat and damage it once they are introduced, as though they’re aggressive, hostile agents out to attack us. Not all new arrivals are dangerous, however. Foreign settlers can bring enormous benefits to their host country. The most common honeybee in America is an immigrant from Italy and has proved invaluable to the country’s food chain. The source of many popular foodstuffs in North America, including cows and orange trees, were once strangers in a strange land.
One lookalike, the native bald-faced hornet, was stabbed with a hunting knife on the desk of a Washington courthouse
Some new arrivals, such as the European starling or Asian carp, do become pests. A study published in 2012 by the US Fish and Wildlife Service, a government agency, estimated that invasive species cause some $120bn-worth of damage each year, almost as much as the entire output of the country’s farms.
Whether new species are hostile or benign, almost all are brought in by human activity. Rats conquered the globe as stowaways on ships. Seeds are carried on the sides of cars. Some species die soon after reaching their new home but many flourish because they find a habitat with no natural predator, or conditions that suit their rapid reproduction. “If there’s a blame game to be had,” said Chris Looney, entomologist at Washington’s agriculture department, “it’s squarely on us as consumers and on the governments that we rely on to protect our borders.”
The giant hornet is not the only recent arrival to threaten America’s Pacific Northwest. Vinegar flies, the common fruit fly which you might find bothering a bunch of bananas, are usually seen as little more than a nuisance: they feed on overripefood that has already been picked, so they aren’t a problem for farmers. The spotted-wing drosophila, a type of fruit fly originally from Asia, is something different. When cherry farmers in California suffered unusually large crop losses in 2008, few people suspected fruit flies could be to blame. The following year many berry producers in Washington found rotting bundles hanging from bushes at picking time, losing up to 50% of their crops.
By the time anyone realised how much damage the tiny, spotted-wing insect could cause, it was too late: elimination was no longer an option; the only path was management. The spotted-wing fruit fly punctures soft-skinned fruit to lay its eggs, and its larvae then eat the fruit around them as they grow. As a result, bushes in this region must be sprayed with insecticide before their flowers even bud, and farmers can no longer grow organic berries.
Track and trace Asian giant hornets can grow to the size of a hummingbird (top). Ruthie Danielsen became a beekeeper in retirement (bottom)
The recent arrival of the Asian giant hornet offered a short window of opportunity to try and curtail its migration. This hunt was given added urgency by the hornet’s habit of building a new nest each year, so that a sighting one season gives little clue about where it may be found the next. But scientists had little expertise to draw on.
Most invasive species were taken to America by European settlers via the east coast. Pigs, gypsy moths and other beasts followed a Manifest Destiny on an animal scale, marching on the west coast through each intervening state. Washington and other western states usually watch that advance from afar and benefit from knowledge gained over generations of incremental migration. This time, however, Washington state is ground zero.
Chris Looney started working as an entomologist for Washington’s agriculture department 11 years ago and has the appearance of someone who moved to Seattle at the height of Nirvana’s success. He is at the vanguard of attempts to combat invasive species, new and old, and finds himself happily cohabiting with the vast majority of the species under his purview. He disturbs neither the spiders that crawl from the bathroom ceiling nor the wasps in his garden.
What’s remarkable about the Asian giant hornet, says Looney, is how little we know about it. Scientists can’t tell you how far they can fly, and whether they stay in one place or migrate after their winter hibernation. All of which means that we can’t predict where future generations of hornets may be found. We also don’t know whether the hornet will establish itself permanently – but it’s certainly possible, given that the cool climate of the Cascade mountains in Washington is similar to that of the hornet’s cradle in the foothills of the Himalayas.
The Asian giant hornet secretes a pheromone from a gland in its abdomen and smears this over the hive, which spells death for the bees within
What we do know is that if the Asian giant hornet establishes a foothold, the consequences may be far graver than a mere shortage of honey. Most of us take the supply of cheap, plentiful food for granted, yet this bounty relies on the abundance of honeybees: industrial crops need beekeepers to provide insects to pollinate the crops; naturally occurring pollinators are too scarce.
If the hornet becomes resident across the country (which it hasn’t yet), and if it primarily relies on slaying bees for its protein, rather than finding more diverse sources (which it may not), then many hives will be obliterated, harvests may shrink and food prices rocket. “We simply do not know how they [hornets] behave in America,” said Looney. “What we do know is that it would be irresponsible not to take action when we can.”
It’s against this backdrop of unknown and uncontrollable variables that a group of environmentalists, professional and amateur, coalesced. Yet it’s a gargantuan job to track and trace a largely unknown, unseen killer. In spring, mated queens build their nest from scratch, laying fertilised eggs that will become sterile female workers. These workers build a nest around the queen, who continues to lay eggs through the spring and summer. Over this time the nest subsists on tree sap and other carbohydrates. Come autumn, the queen begins to hatch the last of her brood: males and new queens. At this stage, the insects’ diet changes and they need protein – and so begins the killing. After the males and new queens mate, the pregnant queens seek shelter to hibernate and begin the cycle anew. The rest of the nest is left to die of old age or cold.
An Asian giant hornet has jaws that can decapitate a bee in a single bite
Mapping the Asian giant hornet’s advance has been near impossible, however: we will never find hornet-zero, the first mated queen to reach American shores, or know what became of her. In that first year after she arrived, she could have been found anywhere within a densely wooded area that measured some 3,000km², roughly twice the size of London.
Since no institution had the resources to scour so much land, in February 2020 Washington’s department of agriculture announced a citizen-scientist programme to help government trappers hunt down the hornet. In the past, volunteers have successfully helped to identify noxious weeds, which can spread across thousands of acres before an untrained eye notices them.
The Asian giant hornet programme, however, was on a far greater scale than previous ones. From July to November 2020, more than 1,000 volunteers, many of them beekeepers, created hornet traps across the state, collected their catch and sent it to the state capital every week. The enemy was in their sights.
Chief among the amateur hornet hunters of Washington state was Ruthie Danielsen. At 65 years old, Danielsen carries herself with the implacable focus of someone with a plan, which, invariably, she has. Her two grey plaits are tied away from her face, as though to remove any distraction. The only time she removed her mask as we talked was to pop a new chiclet of nicotine gum into her mouth (a substitute for the chewing tobacco her Norwegian father plied her with).
Danielsen spent most of her three-decade career working at the nearby oil refinery, currently owned by BP. Planning is her calling, and no industry offers more intricate or ambitious projects than oil. With its compressors, combustion units and ever-burning flares, an oil refinery is one of the most baroque and explosive machines known to man. You can’t just switch off the whole thing when there’s a loose sprocket. For 20 years it was Danielsen’s job to plan for the safe shutdown of the fewest possible parts when repairs needed to be carried out.
Danielsen originally came to Washington in the 1970s to clean up industrial waste with a junkie boyfriend who owned a suck-truck. She herself doesn’t like to be out of control: she doesn’t do drugs or drink alcohol. She doesn’t even eat her own bees’ honey.
The first wave Danielsen’s map of Asian giant hornet sightings and traps (top). Asian giant hornets are so strong they can sometimes climb out of a trap (middle). Ruthie Danielsen has recruited volunteers to hunt for hornets (bottom)
As the only female contractor she was smaller than the others and was often sent to wriggle into tight spaces. One time, while clearing a narrow drainage pipe using her shoulder, her knee got caught in the suction hose. “I’m lucky it caught my leg and not my face,” she said. “It can pull your lungs out of your mouth in less than a second.”
Only once did she refuse a job: a factory manager asked her to clean up a room speckled with drops of mercury. If she breathed in any of it, or even let it touch her skin, she knew she’d be a “goner”. Someone else volunteered, but Danielsen still had to dump the mercury in a nearby river. “It’s a conversation I’ll have with my god, but I’ll spend a lifetime working off the guilt from what I did to that river,” she told me.
She became a tree-hugger – not exactly a conspicuous environmentalist, but someone who will literally hug a tree to sense its calming presence (“If you can’t feel it, you’re either lying or numb”). When her cabin gets infested by rats, she sets live traps with peanut butter, then spends hours collecting the nesting materials they had hoarded, from plexiglass insulation to shoelaces, and sets them free miles from her house, along with their trove.
Retirement is an inadequate description for how Danielsen spends her days. She got hooked on beekeeping after watching a documentary about colony-collapse disorder on a plane back from Alaska in her first year of retirement. “You only get one or two experiences that are so emotional they change your life. For whatever reason, watching that documentary happened to be one of mine,” she said.
The scout will return with a killing squad of between two and 50 hornets the size of hummingbirds
The workshop at her home in Washington is a converted chicken coop with no windows. Scattered throughout are old-fashioned boring tools with wooden gears, tables covered with makeshift beekeeping equipment, lists and notebooks strewn across almost every bare surface. In the corner an easel lists the treatments she is administering to her hives to protect them from colony collapse. A small stack of informational pamphlets, business cards and printed emails is tucked neatly into the front of her spiral-bound notebook. Danielsen is doing what she does best: planning. And right now, she’s planning the downfall of the Asian giant hornet.
Danielsen recruited 42 citizen-scientists to help set traps in the area, and many more joined after media attention on the hornets. But finding the invaders has not been easy. The west of Washington is known for its dense, temperate rainforest. Vegetation proliferates in the rain, mist and fog: firs droop like overgrown beards, trees rise above brush and thick-leaved grass, invasive Himalayan brambles push out new growth over the dead stems of previous seasons. The rest is mown cattle pasture, until you reach the Pacific.
The forest offers countless places for a two-inch-long mated queen to hide during the winter until she gives birth to the workers who will build her a home. Reports from Japan indicate that hornets generally construct their nests in the ground at the edge of forests, in depressions that look like a gopher or snake hole until a giant stinging insect flies out of it, helmeted in bronze like an ancient Greek warrior.
The volunteer crew began to put up snares in July 2020, the formal start of the trapping season, when hornets complete their nests and ready themselves to hunt (Danielsen had been doing this for months on her own initiative). They made traps from clear plastic bottles, in which they cut 4cm by 4cm (1.6-inch) windows on three sides, and then filled them with a mixture of orange juice and rice wine, which Japanese researchers reckoned was the most effective lure. The bottles were hung across a wide area, sturdy lengths of string around the neck to tie them to trees. Danielsen’s group tried other methods too, including putting a mousetrap in a hole in an oak tree.
As the bees emerge to defend their home, the hornets systematically behead them until the hive is bare
In total, citizen scientists maintained almost two-thirds of the 2,470 registered traps. The rest were set up by the state department of agriculture around locations of confirmed sightings. Each week, Danielsen took down the trap on her property and drained its contents through a makeshift sieve – a sheet of mesh secured over the top of a tupperware pot – before dropping off the assortment of insect corpses at a designated site. The traps set to catch the hornets also drown wasps and fruit flies. Normally Danielsen would have been tormented by the thought of harming any living creature, even unintentionally. But the deadly threat to her bees trumped her qualms. “We need to stop this here,” she said.
In November, Looney and I slogged through the mud of a nature reserve owned by BP (Danielsen had helped Looney get permission to collect here). As the road passes by the refinery, it smells of sulphur and burning tyres. The hunting season had finished and Looney was taking down the traps. The brightly coloured, experimental ones in the nature reserve looked alien against the muted rainscape.
The traps were all empty and Looney didn’t know why. It might have been because the weather had been rainy and unseasonably cold. But there were other plausible explanations. Maybe there were no hornets in the area. Or perhaps the traps didn’t work.
The concoction of orange juice and rice wine turned out to be largely ineffective. The traps caught billions of fruit flies, thousands of wasps and a paltry 12 giant hornets. This year teams will experiment with a new bait: a mix of grape juice, rice wine and Calpis, a milky soft drink from Japan. Volunteers can choose to use a more affordable brown-sugar tincture.
“Losing your best hive is like killing a winning racehorse”
The traps themselves were hardly more functional. One trapper spent the season without finding a single hornet until, on October 20th, he found five. Most were still alive so the trapper went to his truck for protective gear before extracting them. When he returned, one hornet had escaped and flown off. Looney suspects that, unlike other insects, hornets may be strong enough to climb out of a trap.
The death toll mounts Ted McFall revisits the site where giant hornets decapitated his bees (top). Chris Looney, entomologist for Washington’s department of agriculture, is in charge of tracking invasive species (middle and bottom)
Instead of writing this off as a failure, Looney studies his mistakes and learns from them. Like many scientists, he sees knowledge as a series of bright, thin glimmers in the darkness of the unknown: answers are best found through the slow grind of data collection rather than speculative assumptions.
Looney’s team did achieve a breakthrough with another experimental tool: a live trap, which insects could easily fly into but didn’t immediately drown in. On three occasions Looney found a live hornet and tried to locate its nest. The first time, he tied a radio tracker onto the hornet’s leg using dental floss. As he and his team followed the transmission through the woods, the signal suddenly dropped. The tracker was never found: the hornet probably gnawed through the floss.
Looney got another opportunity three weeks later. His trapper had found that cluster of five within a 2.5km (1.6-mile) radius, a record number. This time he used a stronger radio transmitter. Entomologists in spacesuit-like protective gear, followed by a documentary crew, traced the radio signal, their eyes glued to the forest floor for signs of the insect.
The pictures show a heap of tiny headless bodies at the entrance of their hive
They lost the signal once, then managed to pick it up again. When they reached the point indicated by the transmitter, they heard buzzing but no one could see the hornets at ankle height. Finally Sven-Erik Spichiger, another entomologist, cast his gaze upwards. He saw a nest tucked in the hollow of a tree, 2.5 metres off the ground.
The nest contained 76 queens. In one swoop, the team from the agriculture department was able to stop each hornet from establishing a nest of its own, preventing the exponential expansion of the hornet population in Washington. But even this success was shadowed by the unknown. Some queens may already have mated and flown away. After the team removed the hive, three more queens were found nearby, dead in a water bucket.
Entomologists suspect that this probably wasn’t the only hive. “In those terms, we failed,” said Looney. “The question is: by how much?” And because the Asian giant hornet builds her nest from scratch each year, the location of sightings made in 2020 are now irrelevant. As new traps are set in July, the team will be as oblivious to the locations of hornets as they were this time last year. The needles will still be in the haystack and the haystack will have been reshuffled.
The forest offers countless hiding places for a two-inch-long mated queen to hide
There are some grounds for optimism. Analysis of frass, as hornet faeces are known, reveals that they eat not only bees but paper wasps and dragonflies too. So it may be that the Asian giant hornet is already finding different protein sources, and won’t exclusively slaughter honeybees to satiate itself.
Despite the best efforts of Washington’s authorities and volunteers, the hornets are likely to destroy more hives. And even if an accommodation is found with the Asian giant hornet, more immigrants are likely to wend their way to America in shipments of goods, by plane or sea. One citizen scientist who has dedicated her professional life to protecting local habitats, is plagued by such thoughts: “What if all I can do is not enough?”
In answer to her own question, she recalled a myth told by the Haida, an indigenous people native to a small group of islands off the coast of British Columbia. A hummingbird, confronted with a forest fire consuming his world, takes water in its mouth and carries it to extinguish one small flame. Perplexed, a big bear asks the hummingbird what he is doing. “What I can,” the hummingbird replies. ■
Ellice Lueders is a writer in Tucson, Arizona
PHOTOGRAPHS: AARON HUEY
