Find out what an Asian hornet looks like and how to spot this stripey alien predator.
I'm guessing most people won't have heard of the Asian hornet. Before I answer the main question "What does an Asian hornet look like?", let me tell you a little more about this unwanted visitor to the UK.
WHAT IS AN ASIAN HORNET?
As its name suggests, the Asian hornet is a species of hornet from Asia. Whilst our UK (European) hornet has evolved as part of our ecosystem, the Asian hornet is an insect out of place.
It is a highly effective predator of other insects. In 2004 it arrived in France and has now spread rapidly across most of Europe and the Channel Islands. It has devastated honeybee colonies and threatens native species of beneficial insects such as bumblebees.
Honeybees are an easy target.
Unlike Asian honeybees, which have had Asian hornets in their world for millions of years, our European honeybees have no natural defences. There are thousands of honeybees in one hive - they are a bee buffet for the hornet.
The hornets will hang around a hive (this is called hawking) waiting for the bees to come out. One hornet can kill up to 50 bees a day. When a weak hive is identified more and more hornets will arrive to hunt.
Their presence stops the bees leaving to forage. It might not fail immediately but it will probably be too weak to make it through winter.
The fear is that Asian hornets will cause damage in the UK if they spread here. This is why beekeepers are so concerned about this insect.
THREE WAYS ASIAN HONEYBEES DEFEND THEMSELVES AGAINST THE ASIAN HORNET
Nature is amazing and this hornet story illustrates that. The Asian honeybee and its hornet predator have evolved together.
Adapted Flight - Asian hornets hawk outside the hive waiting to pick off a returning bee. Generally, Asian honeybees fly slowly side to side as they approach their hive. When the Asian hornet is arround, they fly in quickly, in a straight line - making it harder for the hornet to catch them. They do the same thing on the way out too.
Shimmering - When threatened, hundreds of Asian honeybees gather in a "bee carpet" at the front of the hive. They produce a shimmering effect by shaking their bodies from side to side. The hornet knows it has been seen - it stays further away from the hive.
Balling - If a hornet makes contact with the bee carpet, the hornet is dragged in by guard bees. Thirty or so bees will bite and sting it. Then they form a ball round the hornet. They raise their temperature and kill the hornet by overheating it.
European bees have none of these behaviours. They are easy meat for the Asian hornet.
The Asian hornet is a non-native species that could destroy our pollinators if it becomes established in the UK.
WHAT DOES AN ASIAN HORNET LOOK LIKE?
We all see stripey flying insects every summer. The BBKA (British Beekeepers Association) wants to help people recognise this hornet when they see it.
Our UK hornet is the European hornet (Vespa crabro). It's big (between 2-4cms long) and has large jaws and a loud buzz. Because of its size, it is perhaps rather frightening but it is rarely aggressive to humans.
Its awesome appearance means it is often assumed to be the non-native Asian hornet.
So, what does an Asian hornet actually look like?
Views of the Asian or yellow legged hornet - all courtesy of Giles San Martin under a Creative Commons Licence
The Asian hornet is blacker with a wide yellow/orange stripe on its abdomen. Its legs are yellow. It is also slightly smaller than the European hornet.
The European hornet is browner with much more yellow on its abdomen. Its legs are brown rather than yellow.
ARE ASIAN HORNETS COMING TO THE UK?
Asian Hornets may be able to cross the channel from France or come over in imported pot plants, cut flowers or fruit, and on timber.
The British Beekeepers Association (BBKA) has set up monitoring groups amongst beekeepers and Gloucestershire beekeepers have seen and reported hornets in the past. Concerted action has stopped the hornets spreading for now.
In 2023 there were 28 nests found in the UK. This is a big increase on the last few years (perhaps because Covid travel restrictions kept numbers down in these years.)
You can see a map of recent Asian hornet sightings by following this live link. The map also shows sightings from previous years.
WHEN IS THE ASIAN HORNET ACTIVE?
These hornets are active between April and November BUT activity peaks in August/September when the hornets are building secondary nests. They have lots of young to feed, particularly new queens, so they are busy hunting.
The BBKA's annual Asian Hornet Awareness Week aims to publicise how we can all help spot and report sightings of this damaging insect. It's of concern to beekeepers BUT because of the potential impact on general pollinator biodiversity, this is an insect we should all look out for.
WHAT TO DO IF YOU THINK YOU HAVE SEEN AN ASIAN HORNET?
If you think you've spotted an Asian hornet you can report it via an online Non-native Species Alert.
Alternatively, you can download the free Asian Hornet Watch app. This is available for iPhone and Android. It is simple to use and has a really useful section to help with identification.
Hornets are sometimes confused with wasps and other stripey insects. The app provides pictures of the Asian hornet, the European hornet, the Giant Wood wasp and the Hornet hoverfly to help narrow things down.
CONCLUSION
So, download the app. If you do see something suspect, take a picture. BUT don't annoy the insect by getting too close and certainly don't approach a nest!
Use the app to help confirm the identity then send the picture via the app to report the hornet to the Non-native Species Secretariat. This organisation co-ordinates the UK's response to invasive species such as the Asian Hornet and plants such as Giant Hogweed.
There's lots more information on the British Beekeepers website or check out an excellent blog by Peter Davies, a Regional Bee Inspector, who explains the work he does.
Keep your eyes peeled!
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References:
Information on hornet and bee behaviour plus lots of information for beekeepers on the Asian hornet in Europe and the UK - The Asian Hornet Handbook (2019) - Sarah Bunker, Psocid Press
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