• Asian Hornet Watch app

    Asian Hornet Watch

    It is important to report any suspected sighting of Asian hornets as soon as possible.

    Vigilance is particularly required in southern parts of England and Wales and around major ports.  The Asian hornet is active mainly between April and November and is inactive over the winter.

    For quick identification, please download the Asian Hornet Watch app on either iPhone or Android free of charge.

Training Material

AH tracking etiquette

No trespassing. Use map of local public rights of way.

Parking own car safely, not illegally, not causing obstruction, leave note re AH and contact details.

Don’t leave bait where it could cause concern; if unattended, leave explanatory note and contact with it.

Remove bait when no longer using that station.

Engage with public wherever possible, explain, give leaflet, inform how to report sightings. If living nearby, gauge whether they may like to have a bait saucer on a kitchen window sill and report to you.

AH safety

Avoid getting near nests – occasionally these may be near ground level. A simple bee suit is insufficient. Inform others if low nest suspected.

Suterra looks like pink cordial. It needs a clear label, especially when decanted into another bottle.

Don’t leave bait unattended if it could pose a threat – eg eaten by animals.

Avoid causing undue panic on the part of the public.

Prioritise nests near schools etc.

Avoid lone worker out of contact with others.

 Take care with crossing roads whilst your attention is on tracking.

Take care with climbing on anything, or over anything.

Avoid fields with dangerous animals, especially bulls and cows with calves at foot.

Take care if loose dogs are about.

Avoid sunburn being out in the field all day but remember, that sunscreen and other perfumed products can attract wasps and and hornets so cover up rather than use these products

Tracking Asian Hornets

It is important for us to know how to track Asian Hornets (AH) back to their nests, so that the nests can be eradicated (by appropriately equipped pest controllers).

The experience in France and Spain has been that the number of nests multiplies exponentially, year on year. Every nest that is allowed to reach full maturity in the autumn will produce many new  queens that will hibernate. Each of those will start a fresh nest in the Spring. We need to find as many nests as possible in the early stages of the incursion. It becomes much more difficult to track hornets back to their nest once there are several nests in a small area.

At the moment, the National Bee Unit (NBU) receives funding to track down and eradicate nests, and so far their response has been very effective. Unfortunately, when the number of nests becoming established in one season exceeds the NBU capacity to track down and eradicate enough nests, their funding for tracking will be withdrawn. We need to familiarise ourselves with tracking methods in order to take over from them when their funding is withdrawn. (We would not expect to have to do any eradication ourselves – that is a job for professional pest controllers.)

The NBU are not yet comfortable with the idea of cooperating with volunteer trackers in the field. We are permitted to watch the direction in which hornets fly away from a bait station, indicating the direction of the nest. It is illegal, however, to restrain a hornet, even for a few seconds, to mark it. We have been reminded that that aspect of tracking constitutes “capture and release of an invasive alien species” and requires a permit. (Permits are issued only very selectively at this stage.)

This makes it difficult to judge the distance of the nest when tracking – marked hornets are needed in order to measure timing of return flights between bait and nest. It would be perfectly legal to use a marked hornet if it had been marked without capturing it, but that would be a difficult task – a hornet would fly away rather quickly if it saw a marker pen coming towards it!

In spring 2019, the NBU would like our help with local publicity about AH. They would also like our help with monitoring traps and feeding stations, and would like us to send in photos and sample hornets from these to confirm any sightings.

There is important background information for the UK which will be covered in a comprehensive tracking handbook by Sarah Bunker, an Okehampton beekeeper, to be published in Spring 2019. It would be useful  to read this before doing any tracking here.

TRACKING covers:

–  setting up a bait station

  • checking directions of flight
  • recording those directions on a map
  • timing flights
  • setting up more bait stations using that information, in order to close in on the nest

This sequence has evolved on Jersey and has been successful in enabling volunteers to track nests effectively.

Setting up a bait station:

Hornets will come to the attractant that is used as the bait in wasp traps. Pour the attractant into a dish with absorbent paper for the hornets to land on. Place the dish in a conspicuous position. They may take some hours to find it, so it is not necessary to monitor the new station until a bit later in the day. Once they have learned where it is, they will fly back and forth between the bait and the nest.

Stand well back from the bait while waiting for the hornets to return, to give them a clear view as they get closer.

WATCH THE DIRECTION of flight away from the bait. 

Once a hornet is visiting the bait regularly, watch carefully as it leaves to see the direction in which it flies away. Ideally, use a compass, otherwise note carefully the landmark that best shows where you watched it disappear. You will be able to measure a more reliable direction against a distant landmark than against a nearer one.

The direction of flight will be visible over a greater distance if one’s vantage point is slightly elevated. A bait set amongst trees or very close to a hedge or building may give only a very limited distance of visible flight, so it will be impossible to tell which way the hornet has gone after it disappears around the tree or over the hedge.


Ideally you should have a very large scale map of your area to identify individual properties, fields and clumps of trees. These can be printed from Google Earth preferably on an A3 sized sheet of paper. On your map, mark the precise position of your bait station and carefully draw a line to show the direction of flight. Ideally, measure it with a compass (beware of causes of compass deviation such as a mobile phone or the bonnet of your car under your map!). Otherwise note distant landmarks carefully as the hornet disappears and use those to mark the direction on your map. It is important to observe several hornet flights to confirm the direction of flight before using that to decide on the next step.

Remember as you mark the direction on the map that you have succeeded in tracking hornets only as far as you actually watched them fly. They may have deviated at a nearby landmark as soon as you lost sight of them. They fly at roughly 3 metres per second, so 5 seconds of sight will give you only 15 metres of reliable direction. This means one should not be too optimistic about the nest being in the direction of that observed flight path, and further bait stations will need to be placed ahead stepwise to confirm.


Once they have established a regular visiting routine, start timing accurately how long each hornet spends away from the bait station before returning. As a very rough guide, expect the nest to be 100 metres away for every minute of absence before they return to the bait.

The practice on Jersey (where the capture and release law does not apply) is to mark one or two hornets so that one knows that one is watching a particular individual for the return time. The easiest way to do this involves capturing the hornet for a few seconds. This is the part that is currently deemed illegal without a permit in the UK, but we need to know how to do it in preparation for the stage when the NBU are overwhelmed.

Astonishingly, you don’t need a bee suit or even gloves for marking. Hornets are not defensive when foraging away from the nest. Have ready a “plunger style” queen catcher and coloured markers (Posca markers) as used by beekeepers for queen marking, and place a spot of colour on the thorax (the top of the back between the wings).

However, hornets won’t necessarily fly straight to the nest and back:

~   When first released after marking, they may take a while to develop a regular pattern of visits, especially if they didn’t finish feeding on the bait before capture.

Subsequently, the return times may also be delayed by the fact that hornets may not fly straight to and from the nest:

~   They may have a rest in a nearby tree before setting out.

~   They tend to follow the contour around a hill rather than fly up and over it.

~   They tend to navigate their way by visible landmarks such as hedges, roads and buildings, so may be taking a rather round about route.

~  If the bait is close to, and below, the nest, they may fly away in another direction at first, while gaining height.

With repeated visits to the bait, they tend to develop a more direct route once they have learnt the way. The return times will then reduce and give a more accurate estimate of the distance of the nest. Return times of less than 2 minutes indicate that you are getting very close to the nest. You may never get times of less than a minute because when you are very close to a nest in a tall tree, they will still spend time gaining height.


Once you have consistent return times and direction, move your bait closer to the nest in the direction of the flights.

Depending on the team available, and the terrain, put out another one, or even better, two, more bait stations beyond the estimated distance of the nest, to get hornets flying back in another direction. Having three stations in a triangle enables you to use triangulation, by plotting your three recorded flight directions on the map and, hopefully, seeing the three lines crossing at a point which should indicate the location of the nest. It is not as accurate as the triangulation used in marine navigation, with dependable good lines of sight, because the hornet may change direction after you have lost sight of it. Ideally, the three stations should be in an equilateral triangle, but placing the stations with clear lines of sight along the flight paths is the most important consideration.

We need to bear in mind that accessing property without permission is illegal. If there is no owner/ tenant available to grant permission for access, placing of bait stations needs to be somewhere nearby on ground with permitted access.


Most nests will be found high up in tall trees, but some have been found at lower levels, in hedges and brambles. Avoid getting close to any nest, even in a bee suit, as defensive hornet behaviour can be dangerous.

Many hours can be wasted by starting to look for the nest too soon. It is usually better not to start  looking actively for the nest until one is getting return times well below 2 minutes, or at least a convincing estimate of nest position from three crossing bearings.

Nests high in trees are notoriously difficult to spot from directly under the tree. It may be better to be on the lookout for “traffic” in the form of rapid insect flight to and from an area in the tree canopy, to guide one to a particular tree, and only then to spend time looking up at the tree top for the silhouette of a spherical nest. The nest in a tree that is completely invisible from under the tree may well be more readily visible from a little way off, viewing the tree from the side with binoculars, especially if one can find a high vantage point.

Although marking hornets to measure return times is helpful, and quite easy, one can make good progress without doing any marking, simply by monitoring direction of flight, as long as you report  what you have noted so that others can continue with your work. If the team has information about flight directions from a certain spot, that can be recorded on the map and someone else can come out and mark a couple of hornets so that some helpful timings can be measured.


Place bait station

Watch directions of flights

Check timing of flights

Estimate distance of nests

Place further bait stations to triangulate

Look for the nest.

Further details will be available shortly in the handbook.

Comments are closed.