Invasive Aliens. Dan Eatherley

types of wild bee, it really goes to town on the honeybee, swooping in on hives to pluck off its far smaller quarry. With a (compound) eye on efficiency, worker hornets behead their prey then dismember it, biting off the wings, legs and abdomen, before taking back to the nest only the thorax, stuffed with protein-rich flight muscles – perfect fodder for the developing hornet brood. It’s the entomological equivalent of a shopping trip for prime rump steak, except the hornets do their own butchery.

      In the worst cases, mobs of hornets will linger at the hive entrance, decapitating the emerging bees one after the other until they can move into the colony unchallenged, stripping it of honey, eggs and larvae. The bees back in Asia cobble together a defence of sorts, carpeting the hive entrance and swamping the intruders in a mass of shimmering abdomens. The heat-ball produced by the friction is enough to cook the intruder. The European bees have a go at this too but seem far less effective.

      With the deck stacked in its favour, the Asian hornet has a field day. Over the summer, a single queen produces up to 6,000 young, almost ten times as many as typically found in a European hornet’s nest. Most offspring develop into sterile worker females – the ones wreaking the damage to bee colonies – but around 900 turn into breeding males and 350 become reproductive females, known as gynes, which form the next generation of queens. While many gynes either fail to mate or perish over the winter, a few survive to start new nests themselves the following year. It needs but a handful of these foundresses to succeed for a population to take off, particularly if the new nests aren’t detected and destroyed fast enough.

      And that’s what happened in France. When nests were discovered in built-up areas, local firefighters were called in to remove them, but otherwise the authorities ignored the hornet, perhaps reassured by its lack of obvious threat towards humans. The insect isn’t especially aggressive and its sting no worse than that of the native hornet; in Europe perhaps a half-dozen fatalities to date can be attributed to Asian hornets – a statistic which compares favourably to deaths from wasp stings.

      The honeybee population is less immune: in the Gironde département almost a third of colonies have been weakened or destroyed in a single year, one beekeeper losing 80 per cent of his hives. Dispersing at up to 80 kilometres each year – much further if the foundresses happen to hitch a ride in a passing vehicle – the Asian hornets have advanced unchecked over France. Along the way they have acquired a weakness for seafood, buzzing up and down coastal fish markets in search of small shrimps. It seems that any protein will do. By 2014, they had spread to Belgium, Portugal and Italy. One million of them were estimated to be in Germany. Then, in the early summer of 2016, they were spotted on the Channel Islands of Jersey and Alderney. It was only a matter of time before they reached the British mainland.

      Changing agricultural practices going back a century have devastated Britain’s native bee and wasp populations, wiping out dozens of wild species and putting paid to many a honeybee colony. In recent decades, the threat to these important pollinators has worsened as crops have been drenched in pesticides and diseases have spread. Throw into the mix an exquisitely proficient bee-killer, and things have gone from bad to catastrophic.

      For this reason, the UK government has adopted a zero-tolerance approach. The overriding objective of the Asian hornet response plan, the first of its kind in Europe, is the rapid interception and destruction of the insects before they get established. Beekeepers throughout the land are now on high alert, a select few tasked with active surveillance for the hornet, their colonies designated ‘sentinel’ apiaries. Meanwhile, members of the public are being encouraged to report, including via a mobile phone app, potential sightings of the visually distinctive invader. Unlike the native hornet, which sports a lively pattern of yellows and chestnuts on a dark-brown background, the Asian species is mostly black, save for a band of gold across the fourth segment of its abdomen. Added to that, it looks as if it’s waded knee-high through a puddle of yellow paint. Until now, none of the thousand-plus sightings, routed to the National Bee Unit (located at Sand Hutton, just outside York) for confirmation, have proved positive. But vigilance is key and government-funded bee inspectors are on the front line. A contingency plan – regularly field-tested – is in place. But before it can be executed, a positive identification is needed. In other words, someone has to catch a specimen.

       Tuesday 20 September 2016

      ‘KILLER ASIAN HORNET INVASION’

      ‘SWARMS OF VICIOUS HORNETS SET TO HEAD TO BRITAIN’

      ‘MILITARY-STYLE OPERATION SPARKED TO DESTROY NESTS’

      ‘BRITONS WARNED OF DEADLY ASIAN HORNETS THAT CAN KILL FIFTY BEES A DAY’

      The newspaper headlines that morning were typically understated. But they raised public awareness, and that was the point. In a press release issued the night before, the government confirmed that an Asian hornet had been identified in the Gloucestershire market town of Tetbury, and detailed the urgent steps that would form its rapid response to the invader. These included setting up a three-mile surveillance zone around the town, establishing a command centre at an undisclosed location and deploying bee inspectors to find the Asian hornet nest and pest control teams to destroy it. Emphasising the minimal threat to public safety posed by the hornets, Nicola Spence – the government’s top official for bee and plant health – nevertheless promised ‘swift and robust action’.

       Monday 26 September 2016

      The initial days of the operation proved frustrating. Each morning the inspectors were briefed before heading off in pairs to local apiaries armed with compasses, mobile phones to record grid references, binoculars and purpose-built hornet traps. At each site, the bee suit-clad inspectors hung around for a couple of hours hoping to spot hornets. The team worked off a list – provided by the Gloucestershire Beekeepers Association – which included apiaries at Prince Charles’s Highgrove estate and the Westonbirt arboretum. Some sites were located up to 20 kilometres from Tetbury, the initial surveillance zone having been extended. Perhaps the first sighting had been just the tip of the iceberg. Perhaps multiple nests were out there. But it soon became apparent that the team was wasting time at distant apiaries – the real action was happening less than a kilometre from the original discovery. And not at beehives.

      ‘I’m outside the Tesco’s,’ said one caller. ‘I’ve just seen some of those wasp-things.’ Sure enough, Asian hornets were confirmed buzzing about the red foliage of berberis hedging in the supermarket car park. More were clocked taking aphids from a willow coppice in a private garden nearby. And then this morning St Mary’s Primary School, in the centre of Tetbury, reported them on ivy in the playground, the area in question rapidly cordoned off as the inspectors went to work.

      In predation mode, the hornets seemed oblivious to the fuss. They were not afraid of humans. They just carried on hawking. Inspectors could walk right up to them and stick them in a net. Keeping an eye on the insects as they flew off was trickier. At first, in the hope of improving the hornets’ visibility, the inspectors netted the insects, taped feathers to their abdomens and released them. But the hornets didn’t cooperate; instead they stopped at nearby trees to remove the cumbersome tags and zoomed off. The inspectors got their eye in eventually and abandoned the approach. It was not worth the hassle, you could see a hornet flying without a feather and get a good feel for the direction. After much perseverance, lines of sight were collected. The team was closing in.

       One o’clock. Wednesday 28 September 2016

      Graham Royle, a Cheshire-based seasonal bee inspector, had arrived in Tetbury the night before. He was among those providing relief to the 20-strong task force. More than 100 sites had been visited over the previous week, 50 traps deployed and dozens of fresh hornet sightings authenticated. A total of 94 separate observations would eventually be documented. Graham himself recorded a decent line of sight from a hedge that very morning, having trapped and released a hornet close to some ivy. Just before lunchtime, word came through from the command centre: ‘We’ve got an intersect.’

      As it turned out, the flight lines – four or five good ones – which were plotted on a map didn’t converge neatly at one spot, but the criss-crossing did hint at a patch on the outskirts of Tetbury. Sixteen inspectors congregated in a car