Thursday, April 04, 2019

Defending Britain Against the Asian Hornet

Vespa velutina, the Asian Yellow-Legged Hornet, is an invasive, non-native species, originating from China, that arrived in France in 2004. It spread rapidly and is now established throughout France, Belgium, northern Spain and Portugal, as well as parts of Italy. It a highly effective predator of insects, including honey bees and other beneficial species. Reports from France say that some beekeepers are losing up to 50% of their hives each year, and wild bees and other insects are also being predated in large numbers, with obvious implications for native insectivorous species, such as birds and bats.

In France, as many as 10 nests of V. velutina have been found within a radius of just 600 metres. It is a highly persistent hunter and one of the most adept at catching bees on the wing. It is also likely to cause significant losses to other native insect species, with serious implications for bird populations, already in decline.

All the predictions were that the Asian hornet would make its first appearance in Britain somewhere along the south coast, but in fact it was found far from the south coast or any obvious route of entry. This shows that we cannot take for granted how or where it will try to establish itself.

Prior to 2018, the Asian hornet was found and positively identified (and nests subsequently destroyed) in two locations in Britain: Gloucestershire in 2016 and most recently in North Devon in 2017. During 2018, there were 13 positive sightings, as far apart as Lancashire and Kent and six nests were destroyed. There have been a few other, isolated cases of individual specimens being found. It’s pathway into the country remains unknown, but has clearly not followed predicted trajectories.

As of April 2019, we await the first reports, at the time when any surviving queens will be building their primary nests.

It is known that V. velutina can fly greater distances than the minimum 38km across the English Channel.

Other possible means of entry include:
  1. Imports of timber and bark may conceal fertilized queens
  2. Imports of pottery, especially for the horticulture trade (this is believed to have been its route into France)
  3. Imports of soil, compost and potted plants
  4. Imports of fruit
  5. Imports of bees
  6. Fertilised queens, ready for hibernation, may take refuge in caravans, camper vans, trucks and cars travelling from continental Europe back to the UK, especially in September and October.

Given the rapidity of its spread throughout France, which has more than twice the land area of Britain, once established here it is likely to become widespread and naturalised within a few years. Our climate is unlikely to cause it any significant difficulties, since we are in a similar temperature zone to that of its origins in China.

The Asian hornet is a very real and present danger, not only to British honeybees, but to other bee species, butterflies, moths and more or less all other insects, with implications for the pollination of flowering crops and wild flowers and for all species that depend on insects for food, especially insectivorous birds and bats.

If we do nothing, then sooner rather than later, the Asian hornet will become established in Britain. Further incursions are extremely likely during 2019, given that nobody has any idea where they may next arrive (sentinel apiaries at “high risk entry points” having so far been in entirely the wrong places), or indeed, whether there are already hibernating queens here waiting to emerge and begin nest building.

Current Strategy

There seems to be little published in public view that suggests that this imminent invasion is being taken seriously, with the FERA/National Bee Unit website emphasising the importance of hornet identification, but saying little about what they plan to do to prevent its incursion or how they may deal with it should it become established. Such information is only to be found on the website of the Non-Native Species Secretariat in the form of an Action Plan, which lays out the responsibilities of various government officers in the event of an outbreak and describes in general terms what action would be taken.

However, a gaping hole in the official strategy becomes apparent when we note that in 2017 there were no less than 4,500 reports of V. velutina to the NBU by beekeepers, of which just one was verified (Woolacombe, North Devon) and then only after the beekeeper in question had made considerable efforts to photograph the hornet in order to convince the authorities that he had not been mistaken, as they initially told him he most probably was. This raises the obvious question of how many reports dismissed as false may have in fact been accurate, and - assuming (on no particular grounds) that 95% or more of such reports were indeed false as claimed - also calls into question the ability of the average beekeeper to correctly differentiate the Asian hornet from our native hornet, Vespa crabro, which is distinctly different.

We should question the wisdom of any action plan that seems to rely almost exclusively for its effective deployment on the identification of an exotic, hitherto unseen insect by untrained, unpaid and apparently incompetent people.

It seems that the NBU and the BBKA (British Bee Keepers Association) have failed to communicate effectively with beekeepers regarding the seriousness of this threat and as a result, beekeepers have failed to familiarise themselves with the literature and, in many - if not most - cases, cannot successfully differentiate between a native (and largely harmless) European hornet and the invasive, aggressive Asian hornet.

Another issue arises, which is the question of why has DEFRA apparently made little or effort to ensure that the wider public (i.e. non-beekeepers) is aware of the imminent threat, given the Asian hornet’s propensity for making its home in urban and suburban areas and aggressively defending its nest. Hornet stings are decidedly painful and given the numbers present in a nest, it is likely that children may be put at risk from attack. A number of deaths have occurred in France, most likely from anaphylaxis.

This is clearly not just a potential problem for beekeepers, but is likely to adversely affect a wide range of human activities, including food production, should there be a significant impact on pollination. It also has serious implications for wild bees and many other native species, especially birds and bats.

Further into the Action Plan, we find a good deal of detail about the various meetings that will be organised following an outbreak, and activities that apparently include:

  • Establishing a battle rhythm for the outbreak;  
  • Developing recommendations as necessary for Ministers on strategic direction of response and control policies based on scientific advice from the NBU and Defra’s Chief Scientific Adviser and Plant & Bee Health Evidence Team;  
  • Considering impacts of the outbreak;  
  • Agreeing communication and stakeholder engagement plans;

There follows a comprehensive description of the subsequent action on the ground, involving an unspecified number of staff, majoring on inter- and intra-organisational details, seemingly designed to keep people busy filling in forms for weeks.

In the increasingly likely event of several incidents occurring more-or-less simultaneously across the country, it seems highly likely that the hard-pressed NBU bee inspectors and their DEFRA colleagues will rapidly become mired in bureaucracy at the expense of practical and effective action.

Perhaps the most worrying - and revealing - paragraph in the Action Plan is this one:

37.On receipt of the report(s) from the LDCC, the NDCC will make an assessment on whether it is an isolated outbreak which may be contained. It will then make a recommendation for the SRO and LGD meeting who will then confirm if eradication should be attempted. Isolated means that Asian hornets have only been found in a very limited number of sites in a restricted geographical area (and data from the searches shows a high probability of success in eradication).

No parameters are given for the criteria on which these decisions will be made, which implies that a good deal of “subjective judgement” will be in play. In other words, as soon as the authorities are no longer able to cope with reported outbreaks, they plan to give up the fight.

Beekeepers have been placed in the front line of this battle with little or no preparation or training and no actual weapons. They are being expected to carry out scouting and surveillance operations behind enemy lines and report their findings to a remote HQ, which is more likely than not to distrust and dismiss their findings, while giving no support to beekeepers who could potentially deal with nests themselves, if they had some training.

What Can Be Done - Publicity and Education

While honeybees and their keepers will most likely be the first to feel the impact of the Asian hornet invasion, this is a much bigger issue than just another pressure on bees.

Action is needed to improve public awareness of the potential dangers associated with an unchecked invasion of Asian hornets into Britain. While they may to many people be no more visible than our native hornet, it is likely that they will cause problems for others, particularly outdoor workers, and there is little doubt that they will have a severe impact on our valuable populations of pollinators, including, but not exclusively, our honeybees, which make up approximately one third of the Asian hornet’s diet.

Outdoor workers especially, including farmers, construction workers and both amateur and professional beekeepers, along with bird watchers, walkers, gardeners and other nature lovers, need to be able to spot and identify this insect and differentiate it unambiguously from the native European hornet, not only in order to
expedite essential action, but also to avoid unnecessary destruction of V. crabro nests. Awareness of the need and the means for reporting sightings needs to be increased considerably, or opportunities will be missed.

It is far from clear whether DEFRA has any intention of stepping up its efforts to inform the general public - or, indeed, beekeepers - of the potential disaster that is about to unfold.

What Can Be Done - Technology

Given that beekeepers - like it or not - find themselves in the front line, it seems to me that they should at least be properly armed. The experience of Martyn Hocking, who discovered the hornets in North Devon suggests that photographs are essential if a report is to be taken seriously, so a smartphone or digital camera is a requirement. Spotters should also familiarise themselves with simple methods of taking a bearing from the location at which hornets are seen, in the direction of flight, which will considerably assist nest location. GPS or OS map locations are also important. An app is available for cellphones to make reporting simple.

All of these simple procedures should be well within the scope of most people. However, there is a relatively new technology that can potentially play a significant role both in locating hornet nests and possibly destroying them: the radio controlled ‘drone’, also called quadcopter, hexacopter or octacopter, according to the number of motors fitted. These are now available in a somewhat bewildering variety of shapes and sizes, ranging from tiny, pocket-size toys to hefty, flying platforms designed for cinema-quality video work, civil engineering inspection and even aerial crop-spraying (not yet legal in the UK). Many drones carry cameras, streaming live video to the operator, and could be fitted with thermal imaging cameras, which would be capable of locating hornet nests out of sight of the ground in tall trees.

Drones have two potential applications in this context:

  1. Use of smaller drones to track hornets - most likely by means of trapping a live specimen and attaching a small tracking transmitter (as is routinely done by insect researchers already) - and locating their nests, is obvious. Infra-red cameras can be used to locate nests from above, where visibility from ground level is restricted.

  1. The possibility of using them for actual nest destruction is there, but a lot of work needs to be done before it can be viewed as a routine procedure. Large drones, fitted with ingenious, home-made gadgets, have successfully been used in France to inject powdered insecticide directly into hornet nests.

Clearly, while injecting a toxic substance directly into an enclosed nest is likely to be effective at killing hornets, the residue is also likely to be as effective at killing non-target insects, as well as birds and bats. Other possibilities for nest destruction include the injection of a gas or vapour in order to kill the inhabitants without leaving a toxic residue. Carbon dioxide and steam are both under consideration.

Action is Needed Now

The lesson from France is that early action is essential, before the problem gets out of hand. We only have one chance to defeat this pest, which is to prevent it from becoming established. I understand that work is underway to find long-term solutions, including genetic engineering of one sort or another, but there are no guarantees of success and meanwhile this insect could inflict devastating damage on our bee population and aggravate the already serious decline of birds.

While government officials will, no doubt, do their best within the constraints imposed on them by budgets and manpower, the scope of their actions is highly unlikely to be adequate to deal with a persistent, adaptable invader.

Opportunities to work alongside the NBU seem currently to be virtually non-existent, as they are adamant that “it is no longer possible for beekeepers to accompany bee inspectors, under any circumstances” (quoted from an NBU representative, speaking at a meeting called by beekeepers to discuss the Asian hornet threat, Saturday January 20th 2018). Therefore, we need to educate and equip ourselves, share knowledge and experience, and make use of the technology that has recently become available and accessible.


An informal, but well-informed and competent task force needs to be organised, comprising motivated individuals with technical skills (including academics, professionals and enthusiastic amateurs), who can pool knowledge and work on a variety of approaches to the location, identification and destruction of Asian hornets. Some funding will be needed to prime the pump, and it may be possible to “crowd-fund” the project once we have something to show for our efforts.

In practical terms, we need to to contact and, where practical, visit people with appropriate skills and experience and report findings to an accessible online location. I have made a start by setting up a this page on FaceBook to begin the process of communication and coordination.

Work needs to be started on identification, tracking, location and nest destruction protocols. Specifically:

  1. Given that Asian hornets are most likely to be seen around beehives, we need to develop methods of identifying them quickly and effectively, using some of the range of sensors currently available. Most promising sensors so far are: colour recognition; sound detection and filtering; ultrasound; thermal signature.
  2. Live trapping will be the key to our ability to track insects back to their nest, once they have been tagged. Some work is being done elsewhere (Italy, I believe) using harmonic radar, but this may prove too expensive for our purposes. It may be possible to attach small radio tags (RFIDs) to a hornet without significantly impairing its ability to fly, enabling it to be tracked by a drone equipped with a receiving device. This is a potential low-cost solution.
  3. Infra-red cameras mounted on drones have successfully been used in Portugal to locate hornet nests where visual observations from the ground proved ineffective. This technology is available at moderate cost. Harmonic radar shows promise, as this is already used experimentally to track some insects, including hornets.
  4. Various means of destroying nests are currently used in France, including shotguns, high pressure water spraying and injection of pesticide directly into the nest using relatively large drones. The height and inaccessibility of nests often make all but the latter impossible, while it is clearly undesirable to fill a nest with pesticides, which will leak into the environment as the nest collapses, with considerable collateral damage to other species, possibly including humans. I suggest we investigate the use of non-polluting gases, such as carbon dioxide, and steam. Either of these could be delivered to the target using suitable drones.

The ethos of this project is very much one of “open source” (sharing experimental procedures, coding and data freely) to enable full participation by anyone who is willing and able to play a part.


I have already committed my limited resources to this project, alongside my other beekeeping activities, both in terms of time and money. I already have most of the tools and equipment I need and have made preliminary experiments with sensors and single-board computers (Arduino, Raspberry Pi, etc). I have made a start on identifying others with complementary skills, as team work will be important.

However, although I have time and technical skills, I do not have the means to buy the equipment needed to carry out the vital, real-world experiments with drones, infra-red cameras and tracking devices.

If there are indeed hibernating queen hornets already present in the UK, they will already be building their primary nests, so we need to move quickly.

Philip Chandler
Friends of the Bees CIC