The Asian hornet (Vespa Velutina) is not native to the UK. The Asian hornet also known as the yellow-legged hornet, is a species native to Southeast Asia. In recent years, it has become an invasive species in Europe, causing significant concern for the UK’s ecosystem. This comprehensive article will explore the biology, behaviour, and ecological impact of this aggressive and adaptable insect. We will also delve into the measures taken to control and manage the presence of Asian hornets in the UK, as well as the potential consequences if left uncontrolled.
The Asian Hornet
The Asian hornet is a member of the Vespidae family and is slightly smaller than its European counterpart, the European Hornet (Vespa Crabro). Adult workers measure between 25 and 30 millimetres, while the queen can reach up to 35 millimetres in length. It has dark legs with yellow tips, a dark thorax and a dark abdomen that has an orange/yellow band at the end. Its head is dark from above, orange from front. It is completely silent in flight. It is never active at night.
Life Cycle and Nest Construction
The life cycle of the Asian hornet begins when a fertilised queen emerges from hibernation in early spring. She builds a small nest, usually in a sheltered location such as a tree cavity, hedge, or building eave. Here, she lays her eggs and raises her first generation of workers. Once these workers hatch and mature, they take over foraging and nest construction duties, allowing the queen to focus solely on laying eggs. Over the summer, the colony grows exponentially, with the nest reaching sizes of up to 1 metre in diameter and housing thousands of hornets.
Asian Hornet Nests
The nests are constructed from a mixture of plant material and hornet saliva, which forms a papery substance. The nests consist of multiple layers of hexagonal combs, each containing larvae in various stages of development, and are covered in a protective outer envelope.
Feeding Habits and Predatory Behaviour
Asian hornets are diurnal predators, feeding primarily on other insects and arachnids such as flies, moths, wasps, and spiders as well as a vast array of other invertebrates. These predators have adapted remarkably well to our environment. They will feed on any protein source they can find. However, they are particularly notorious for preying on honeybees, which poses a substantial threat to honeybee populations and the pollination services they provide.
Yellow-legged hornets employ a hunting technique known as “hawking”, where they hover outside the entrance of a bee colony and capture returning forager bees in mid-air. They then proceed to dismember the captured bee, discarding the head, legs, and abdomen, and return to their nest with the protein-rich thorax to feed their developing larvae.
Around 30% of their diet consists of honeybees. This is likely because honeybees live in large colonies and are relatively easy prey for them.
Each Yellow-legged hornet nest will consume between 11- 12 kg of prey per year. This roughly equates to the weight of a car tyre or to 90,000-100,000 insects and pollinators.
If allowed to establish here in the UK, the potential devastation to all agriculture and the delicate ecological balance, resulting from the loss of pollinators and a vital protein source in the food chain, will be irreversible for many years, if ever. The cost to the UK economy would be measured in billions of pounds.
Serious allergic reaction (anaphylaxis): Anaphylactic shock is a serious condition and urgent medical assistance should be sought. Symptoms and how to deal with anaphylaxis are on the NHS website.
Invasion Background Europe & United Kingdom
Europe
The first sighting of the Asian hornet in Europe was recorded in France in 2004, likely arriving through an accidental importation in a shipment of pottery from China. The hornet rapidly spread throughout France, establishing a stronghold and further expanding its range to neighbouring countries, including Spain, Portugal, Italy, Belgium, and Germany. The first official sighting of the Asian hornet in the UK occurred in 2016 in Tetbury, Gloucestershire.
United Kingdom
The first Asian hornet nests in Hampshire were found in September 2018 along with nests in other parts of the UK. Other Asian hornet nests are likely, and vigilance is absolutely essential. Once established, this species will be very hard to eradicate. It is an extremely aggressive predator and a colony of Asian hornets will decimate a colony of honeybees in a few hours. A single queen will establish a colony early in spring and will raise thousands of worker hornets and hundreds of young queens, which will come through winter and start their own colonies.
Yellow Legged Hornet (Vespa Velutina)
European Hornet (Vespa Crabro)
The European hornet (right) is native to the UK and is not a threat. The worker is up to 30mm long with brown legs. It has a black thorax with extensive brown markings, and a yellow abdomen with brown markings on the upper side, not banded. Its head is yellow from above an from the side. it buzzes loudly in flight. The European hornet sometimes flies after dark.
See It, Snap It, App It.
‘REPORTABLE’ means that, by law, you must report any sighting to the appropriate authority (the Non-Native Species Secretariat, NNSS):
- by using the Android or iPhone app which can be downloaded from the National Bee Unit Web Page, or
- by using their Online Sighting Form, or
- by email to alertnonnative@ceh.ac.uk
The Yellow-legged (Asian) Hornet is not an issue exclusive to beekeepers. This is a public menace; it will affect millions of us, from farmers to fisheries, from gardeners to ground-keepers, from open-air markets to alfresco dining.
If you are a beekeeper, try to allow an extra 10 to 15 minutes when you visit your bees. Just stand or sit and watch the hive entrances because the Asian hornets’ hawking behaviour is instantly recognisable.
If you use a monitoring trap, remember that releasing a trapped Asian hornet is illegal. Just take a photo and report it as instructed, then freeze it for authorised experts to examine.
Whether you are a beekeeper or not, use the Asian Hornet Watch app to verify the identity of the insect. Take a photo, and report the sighting using the app. Share the identification details with friends, family, and colleagues. Together we can eradicate this menace from our shores.
A useful identification chart can be found at the National Bee Unit Website, from which these images were taken.
ON NO ACCOUNT SHOULD YOU APPROACH OR ATTEMPT TO REMOVE AN ASIAN HORNET NEST. This insect has a highly potent 8mm sting that is not barbed, so she can and will sting repeatedly, and the pheromones released will summon her nest-mates to join the attack. Report your sighting using the advice above.
If you use a monitoring trap, remember that releasing a trapped Asian hornet is illegal. Just take a photo and report it as instructed, then freeze it for authorized experts to examine.