The reason for the rise in numbers is simple: there is a booming population along the coasts of France and Belgium. Asian hornets are stowing away in lorries and, occasionally, holidaymakers\u2019 cars and reaching us via ferry. Some experts also believe that, with favourable winds, a hornet could cross the Channel by itself.<\/p>\n
The Asian hornet is smaller than the UK\u2019s native European hornet (which has a more gingery hue), but larger than a queen wasp. It is blacker in appearance than our native hornet and wasps and sports distinctive yellow legs and an orange face. Its abdomen is mostly black, except for one thick orange band; our native hornet\u2019s abdomen is more yellow than black.<\/p>\n
Both hornet species are mostly carnivorous \u2013 their diet is other flying insects \u2013 but whereas the European hornet has evolved alongside existing insect populations, the Asian hornet is new to Europe. Its population explosion suggests its numbers are not being kept in check by natural predators or pathogens.<\/p>\n
Beekeepers are particularly concerned. Asian hornets have been widely observed hovering outside beehives and picking off worker bees as they emerge. \u201cA honeybee hive is like a supermarket for the hornets,\u201d says Campbell.<\/p>\n
One Asian hornet can hunt and consume up to 50 bees in a day, but their collective impact is most significant. Asian hornet nests are unusually large; they can grow to the size of a watermelon by late summer. Each can contain 3,000 hornets. A French study found that a single Asian hornet nest consumes 11.3kg of insects each summer. A typical honeybee weighs 116mg. \u201cThat\u2019s a heck of a lot of insects in an environment where we are already worried about falls in insect populations,\u201d says Campbell. \u201cThe impact on biodiversity could be very significant.\u201d<\/p>\n Apart from killing honeybees, the presence of predatory Asian hornets causes worker bees to go into \u201cforaging paralysis\u201d: they hide in the hive, failing to acquire enough nectar and pollen to survive winter. It is difficult to determine the precise impact of the hornets\u2019 arrival, because so many variables shape honeybee productivity. In Portugal, beekeepers in some regions claim 50% of their hives have been lost because of Vespa velutina; French beekeepers attribute 29% of honeybee colony mortality to the hornets.<\/p>\n The economic impact is widespread. In continental Europe, ripening fruit in vineyards and orchards has been despoiled by Asian hornets, posing a threat to wine and fruit production. In France, some outdoor markets have had to move indoors because the hornets are attracted to the fresh fruit, fish and meat.<\/p>\n There are also fears for public health. Early summer nests can be built fairly low to the ground, before colonies move high into trees in late summer. Spring queens are not particularly aggressive \u2013 they have a colony to build \u2013 but if someone stumbled into a nest at ground level it could be catastrophic. When the hornets establish themselves in Britain, those who work outdoors \u2013 farmers, gardeners, railway engineers \u2013 could be vulnerable. Deaths have been reported in France after allergic reactions to multiple stings, but there is no reliable data.<\/p>\n Some question this narrative of fear. Chris Packham has argued in the Guardian that there are worse threats to biodiversity than these \u201cbrutal bovver buzzers\u201d, most notably the cocktail of pesticides sprayed over British farmland, including those banned by the EU. Some scare stories have been inaccurate, instead evoking the Asian giant hornet, which is a separate species, Vespa mandarinia, the tropics-loving \u201cmurder hornet\u201d now terrorising parts of North America. This species is unlikely to establish itself in the UK because the climate is too cold.<\/p>\n So, how worried should we be? Relatively few scientific studies have quantified the Asian hornet\u2019s impact on biodiversity and insect abundance so far, but scientists are taking the convincing, albeit mostly anecdotal, evidence seriously. \u201cEcologically, yes, it will alter things. I don\u2019t think it\u2019s going to be devastating,\u201d says Seirian Sumner, a professor of behavioural ecology at UCL. \u201cUnless you are a honeybee farmer, you probably don\u2019t need to worry too much. I worry on behalf of the other social wasps, because they represent a significant proportion of their diet, but I\u2019m sure I\u2019m alone in that.<\/p>\n \u201cI also worry about how it\u2019s going to affect public perceptions of wasps and hornets. We are at a time where we need to be encouraging people to embrace every facet of nature, no matter how revolting or scary, because every part of an ecosystem has a role to play. And we are the cause of all these invasive insects.\u201d<\/p>\n A scientific study examining the hornet\u2019s impact on the native buff-tailed bumblebee found that the hornets could catch the bee and start to fly off with it, but the bee would then drop to the ground, pulling the hornet down with it. \u201cIt seems that bumblebees have this evolved behaviour that is already giving them a defence and resilience,\u201d says Sumner.<\/p>\n Britain\u2019s defences against the hornet have been criticised by some, but many experts, including beekeepers and scientists, defend the efforts of the government\u2019s NBU and the Non-Native Species Secretariat, which highlights the dangers of invasive species inadvertently brought to Britain, such as Japanese knotweed. Many Asian hornet media stories have been triggered not by a predilection for scaremongering, but by this government-led drive to encourage the public to report Asian hornet sightings so that the species can be held at bay.<\/p>\n The government is still committed to \u201ceradication\u201d, but future scenarios include \u201ccontainment\u201d and then the \u201cnew normal\u201d \u2013 accepting that the Asian hornet is here to stay. Prof Helen Roy of the UK Centre for Ecology and Hydrology is impressed that this effort has prevented the species\u2019 establishment for eight years. \u201cHopefully, the same will happen this year. Prevention is by far the most important way to address the threat of invasive species,\u201d she says. \u201cWe are right to consider invasive species as one of the main five drivers of biodiversity loss. And social insects, such as Vespa velutina and ant species, are a particular concern. There is good evidence of the impact that they are having on native biodiversity.\u201d<\/p>\n In 2022, there were 8,000 potential sightings, reported mostly via the free app Asian Hornet Watch. Last year, 20,000 potential sightings were investigated by verifiers; only about 150 of these sightings turned out to be genuine. The NBU\u2019s 60 officers were then dispatched to destroy nests. \u201cPeople still struggle with its identification \u2013 and that\u2019s understandable, because insect ID is not straightforward \u2013 but I feel really inspired by the citizen science and people\u2019s willingness to get involved,\u201d says Roy. \u201cThe beekeeping community have been amazing at raising awareness as well.\u201d<\/p>\n Campbell fears that this year could determine whether the government continues its eradication policy or is so overwhelmed by sightings that it has to resort to containment. \u201cThere were tensions last year when the speed and scale of responses didn\u2019t always match the threat level,\u201d he says. \u201cWe know the NBU is a small unit and we know this is a once-in-a-lifetime opportunity to stop the hornets establishing. Once they are established, it will be nigh on impossible to get them out.\u201d<\/p>\n Technology may help. Scientists at the University of Exeter have developed VespAI, an automated bait station that alerts operators to the presence of Asian hornets. The hornets can also be caught and fitted with miniature radio tags so that they can be tracked back to their nest and the whole colony can be destroyed. More low-tech, but admirably effective, are silver streamers that Jersey\u2019s hornet hunters have developed, which they attach to hornets that they catch and release. The streamers enable the hunters to track them more easily by sight, quickly locating nests.<\/p>\n As with most challenges posed by invasive species, the country where biodiversity has been most blitzed by rogue introductions, New Zealand, is pioneering innovative responses. It has been plagued by the common wasp (Vespula vulgaris), which we accidentally sent them in the 20th century. The wasps\u2019 predation of aphids has altered the ecological balance of entire forests. Researchers are seeking to develop gene drives to produce sterile male wasps. Could something similar be developed here for the Asian hornet? Scientists are cautious; there is a long history of comparable biological controls producing unintended, unwanted consequences.<\/p>\n The invertebrate charity Buglife argues that we must eradicate the pathways by which such harmful invasive species arrive. \u201cThe Asian hornet is a poster child for invasive species. We can\u2019t let this be the first of many \u2013 it needs to be the last,\u201d says David Smith, Buglife\u2019s advocacy and social change officer. \u201cAddressing those pathways means we are probably going to capture or prevent more species from arriving, rather than focusing solely on a handful of species.\u201d<\/p>\n Although the Asian hornet appears to be mostly coming to Britain on ships, its arrival also highlights the dangers of importing goods \u2013 particularly plants \u2013 in soil. \u201cThere are some easy biosecurity steps that are being ignored,\u201d says Smith. For instance, the EU has banned British exports of plants in soil, but Britain still accepts the importation of plants in soil, bringing unknown animal life hidden in soil straight into garden centres and nurseries. \u201cHow about we make it two-way and increase our biosecurity?\u201d says Smith.<\/p>\n A government action plan for better biosecurity has been drafted for some time, but it is still awaiting consultation, let alone being introduced. \u201cThere is a lack of attention, lack of focus and a lack of bringing [animal biosecurity] up to the standards of plant health,\u201d says Smith. \u201cIt\u2019s not an experiment we can afford to do. We can\u2019t let the Asian hornet be this moment in time where we go: \u2018It\u2019s here now, we\u2019ll deal with the next one when it arrives.\u2019 It should be a real warning that others are waiting in the wings, particularly with the climate crisis.\u201d<\/p>\n