Last year, there were record sightings of Asian Hornets in the UK, posing a threat to honey bees and other pollinators. Although native to Southeast Asia, Asian hornets arrived in France in 2004, most likely in a shipment of imported goods.
Once in France, they spread rapidly, and have continued to move to adjoining countries. As of December 2022, Asian hornet is established in Spain, Belgium, Netherlands, Portugal, Italy, Switzerland, Germany and Jersey.
The first Asian hornet was discovered, in the UK Tetbury, in 2016 – and the nest was later found and destroyed. However, there have been further sightings in subsequent years.
While Asian hornet nests rarely survive colder winter temperatures, researchers say that this year, the invasive species have survived the UK winter for the first time – and may be set to settle in the UK permanently.
So what exactly are Asian hornets, why are they a problem, and what should you do if you see one?
What are Asian hornets?
Asian hornets, also known as Vespa velutina) are a species of hornet indigenous to Southeast Asia. They look different to European hornets in that they have…
- darker (black or dark brown) velvety heads and bodies
- a distinctive wide orange stripe on the fourth section of their abdomen
- yellow leg ends that look like they’ve been dipped in paint
Asian hornets also tend to be smaller than European hornets. Queens can be up to 30mm long, while workers may be up to 25mm long. People who’ve encountered Asian hornets have also described their buzz as more of a “growl” sound.
The video below from the Animal & Plant Health Agency can help with identifying Asian hornets…
The government has also produced an ID sheet, which you can download as a PDF below.
Asian hornets are most active between April and November – making sights more likely during this period – and inactive during winter when they die or enter hibernation.
Why are Asian hornets a problem?
The biggest issue with Asian hornets spreading across Europe is the deadly threat they pose to honey bees and other insect pollinators – which could harm the functioning of our ecosystem.
Each Asian hornet eats 50 honey bees a day and up to 11 kg of insects a year – and, shockingly, a swarm of Asian hornets can destroy a hive of up to 30,000 honey bees. According to the National Bee Unit, Asian hornets destroyed 72 nests in 56 locations in 2023, most of which were in Kent.
Why have Asian hornets survived a UK winter for the first time?
The National Bee Unit took DNA samples from hornets caught this year in traps in the Kent area. The tests showed that these were the offspring of a nest destroyed in 2023 in nearby Rye – proving that Asian hornets are capable of overwintering here in the UK.
A single hornet nest can produce 350 queens; and while 90% of these won’t survive winter, each fertilised queen that does can form an entirely new colony. Each queen also hides herself well over winter to be less likely to be disturbed. When a queen is woken up from hibernation early, it’s nearly impossible for her to re-enter her deep sleep and she will die from starvation.
The prime time for a queen to wake up is mid-April when she can begin feeding on nectar to replenish her fat reserves and activate her ovaries. The next stages will involve her seeking a nesting site to begin laying her eggs and building her hive.
For this reason, the British Beekeepers Association are working quickly to find other Asian hornet nests before new queens are produced.
Are Asian hornets harmful to humans?
The government has advised that Asian hornets pose no more risk to humans than native/European wasps and hornets. However, they’re particularly defensive of their nests and can deliver a painful sting if they feel threatened – sometimes attacking in groups.
Asian hornet stings generally pose no long-lasting or serious risk to humans. But, in rare cases, where someone is allergic to their sting, uncomfortable symptoms such as difficulty breathing, hives, and swelling may appear.
In even rarer cases, where an allergy is severe, a person may go into ampholytic shock – a life-threatening condition where the airways narrow, blood pressure drops suddenly, and breathing becomes difficult.
What should you do if you find an Asian hornet?
You should notify the Great British Non-Native Species Secretariat (NNSS) when you see an Asian hornet, so that measures can be taken to help prevent their spread.
You can do this by…
- Downloading and using the Asian Hornet Watch app – available on Android or iPhone
- Filling out an online recording form
- Emailing [email protected]
It will help if you can provide details of where you found the Asian hornet, as well as a photo and clear description. And, in the meantime, remember to stay vigilant and keep an eye out for any additional Asian hornets in your area.
You can also keep up to date with sightings of Asian hornets in the UK by heading to the government website.
While the National Bee Association has offered guidance on how to trap and kill Asian hornets, the Department for Environment, Food, and Rural Affairs (DEFRA) has also warned: “It is important to take care not to approach or disturb a nest.
“Asian hornets are not generally aggressive towards people but an exception to this is when people perceive a threat to their nest.”
So far the NNSS has reported that people should be most vigilant in southern parts of England and Wales, and around major ports.
What to do if you’re stung by an Asian hornet
While Asian hornets generally don’t sting unless they’re provoked, if you do get stung, health experts advise washing the area thoroughly with soap and cool water. Applying ice will also reduce swelling and inflammation, and stop the venom from spreading further.
Asian hornets don’t leave a stinger so you don’t need to worry about removing one.
If there’s a risk that you could be stung again, you should also do what you can to leave the area quickly and calmly.
When should you see a doctor after an Asian Hornet sting?
If you get stung multiple times or notice signs of an allergic reaction, then it’s important to seek medical attention. This is especially true if you have trouble breathing after being stung.
For more advice about what to do during an allergic reaction to bee and wasp stings, you can visit Anaphylaxis UK’s website.
Interesting facts about Asian hornets
- Asian hornets are strong fliers, which is largely why they can spread so quickly. In France, they’ve spread at roughly 100km per year.
- Asian hornet nests can measure 60-90 cm in height and 40-70 cm in diameter. Each one has an exterior shell made of 5-6 layers of paper mache-like material, which is beige or brown in colour. Inside these layers are six or seven ‘cell cakes’ where the Asian hornets live. They enter and exit the nest via a single entrance hole, which is protected by an awning.
- Since 2003, when the Asian hornet made itself at home in South Korea, it’s become the country’s most abundant species. In doing so, it’s displaced many other native hornet species.
- Other hornet and wasp species that could weaken and kill honey bee colonies include: Asian giant hornets, oriental hornets, European hornets, lesser banded hornets, Japanese hornets, and black shield wasps.
Final thoughts…
With the news that Asian hornets have survived a UK winter for the first time, it’s looking like they might be set to become permanent residents. However, the threat this would cause to our honey bee populations and, therefore, our ecosystem, means that the appropriate authorities are keen to act quickly to stop the spread.
If you spot an Asian hornet, it’s important to keep yourself safe and report it as quickly as you can.
Have you seen an Asian hornet? We’d be interested to hear from you in the comments below.