Roe Valley Beekeepers Association
The Asian Hornet
Vespa velutina, the yellow legged hornet, commonly known as the Asian hornet, is native to Asia and was confirmed for the first time in the South West of France in 2004. It was thought to have been imported in a consignment of pottery from China and it quickly established and spread to many regions of France. The hornet preys on honeybees.
In 2016, the Asian hornet was discovered in the UK for the first time, in Tetbury. After 10 days of intensive searching, the nest was found and later destroyed and on the same day, a single hornet was discovered in a bait trap in North Somerset. Genetic analysis has confirmed that the hornet nest found in Tetbury and the dead hornet found in North Somerset were of the same genetic population (Vespa velutina nigrithorax) as those which came from Eastern China to France.
Appearance and biology of the Asian hornet
Vespa velutina (Asian hornet) is smaller than our native hornet, with adult workers measuring from 25mm in length and queens measuring 30mm. It's abdomen is mostly black except for it's fourth abdominal segment which is a yellow band located towards the rear. It has characteristical yellow legs which accounts for why it is often called the yellow legged hornet and it's face is orange with two brownish red compound eyes.
After hybernation in spring, the queen, usually measuring up to 3 cm, will emerge and seek out an appropriate sugary food source in order to build up energy to commence building a small embryonic nest. During construction of the nest, she is alone and vulnerable but she will rapidly begin laying eggs to produce the future workforce. As the colony and nest size increases, a larger nest is either established around the embryonic nest or they relocate and build elsewhere.
During the summer, a single colony, on average, produces 6000 individuals in one season. From July onwards, Asian hornet predation on honeybee colonies will begin and increase until the end of November and hornets can be seen hovering outside a hive entrance, waiting for returning foragers. This is the characteristic “hawking” behaviour. When they catch a returning bee, they will take it away and feed off of the protein rich thorax; the brood requires animal proteins which are transformed into flesh pellets and then offered to the larvae.
During autumn, the nest’s priorities shift from foraging and nest expansion to producing on average 350 potential gynes (queens) and male hornets for mating, however, of these potential queens, only a small amount will successfully mate and make it through winter. After the mating period, the newly fertilised queens will leave the nest and find somewhere suitable to over-winter, while the old queen will die, leaving the nest to dwindle and die off. The following spring, the founding queen will begin building her new colony and the process begins again.
In light of the Asian hornet finding in the UK in September 2016, it is imperative that you know how to recognise and can distinguish them from our native hornet, Vespa crabro
Confirmation of an Asian hornet find in Scotland suggests a need to prepare for monitoring, for the arrival of the Asian hornet to Ireland. UBKA strongly encourages all beekeepers in Northern Ireland to monitor for the Asian hornet. This can be achieved by making a simple trap. Some helpful tips and advice on how to make your own trap can be found in the BeeBase fact sheet, clicking here will give an automated download Asian hornet monitoring trap
BeeBase has also given Information from beekeepers in France that shows that nest numbers are reduced by > 90% in areas where traps are deployed in springtime. Should the Asian hornets become established anywhere in this part of the UK or ROI, springtime trapping will thus be a very useful management. When hanging out traps, please remember that it is important that damage to native Irish wasps, hornets and any other insects is kept to an absolute minimum.
It is important to report suspect sightings immediately to the Invasive Species Ireland website www.invasivespeciesireland.com/alien-watch/. and forward suspect samples to AFBI for confirmed analysis to ensure follow-up. Suspect samples found in Northern Ireland should be forwarded to the AFBI with the senders contact detail and addressed to: Ivan Forsythe, Entomology Laboratory, The Agri-Food and Biosciences Institute, 18a Newforge Lane, Belfast BT9 5PX.