The yellow legged or Asian hornet could rapidly colonise the UK, representing a serious threat to bees, unless its spread is combatted, according to new research by the Universities of Warwick and Newcastle, working with the National Bee Unit.

The insect, a nest of which was detected in Gloucestershire last year, preys on honey bees and other potentially beneficial insects. Based on research published in the journal Nature Scientific Reports this month, Professor Matt Keeling, from Warwick's Zeeman Institute for Systems Biology & Infectious Disease Epidemiology Research (SBIDER), predicts that if Asian hornet nests are left to thrive in the UK, there could be hundreds of thousands of them in just over two decades - putting a critical strain on British populations of honey bees and other beneficial insects.

In March, the government launched an app for people to report Asian hornet sightings, following the furore surrounding the case in Gloucestershire. This was the first confirmed nest in the UK, though Asian hornets have been present in France since 2004, and have since spread to Italy, Spain, Portugal, Switzerland, Germany and Belgium

As part of their research, Warwick and Newcastle scientists simulated the likely spread of Asian hornet across the UK over a twenty-five year period, starting from a single active nest in a location near Tetbury, Gloucestershire (the site of the nest that was discovered and destroyed last year). Prof Keeling used recent data from the Andernos-les-Bains region in South-West France - where there has been detailed observation and destruction of Asian hornet nests over the past eight years.

He said, "Our research shows the potential for this predator to successfully invade and colonise the UK, spreading rapidly from any new invasion site. Even if we have managed to successfully control this first invasion, the presence of a growing population of these hornets in Northern Europe makes future invasions inevitable.”

Prof Keeling believes that the spread of Asian hornets in the UK - and the effect this would have on bee populations, which are already under considerable strain - could be halted if beekeepers and the general public (especially in the South-West) are vigilant, and able to identify the insects.

Dr Giles Budge, from former government research agency Fera Science and Newcastle University, added, "Our work highlights the importance of early detection for the successful eradication of this hornet. To do this, we need members of the public and beekeepers to familiarise themselves with this hornet, look out for signs of foraging hornets particularly near honey bee colonies, and check the tallest trees for their large nests. Rapid reporting could make all the difference between eradication and widespread establishment."

Asian hornets are smaller than the UK’s native hornets, with adult workers measuring from 25 millimetres in length, and queens measuring 30 millimetres. Their abdomen is mostly black apart from the fourth abdominal segment, which has a yellow band located towards the rear. The hornets have yellow legs, and an orange face with two brownish red compound eyes. Most of the reported sightings in the UK in 2016 were of native hornets.

In spring, surviving Asian hornet queens begin a small nest, often in a sheltered location such as in the eaves of a roof or in a garden shed. Here they raise the first clutch of workers who take over the queen's foraging duties. At this stage the nest grows quickly, and the hornets often move to establish a secondary nest where there is more space to expand. These nests can become very large, and are often located high up in the tree canopy, close to a food source such as apiaries.

Anyone who finds a suspected Asian hornet or nest can contact the Non Native Species Secretariat immediately using their alert email address: alertnonnative@ceh.ac.uk, giving as much detail as possible, including the location where the hornet was found and if possible an image of the suspect hornet.

The hornet identification smartphone app is available to download here.

A confirmed hornet sighting will trigger an eradication plan by the National Bee Unit, who are using the results of this research to help focus search efforts.