Tracking down an Asian hornet nest · step by step with a wick jar
Reporting an Asian hornet takes five minutes. But a report of a single insect does not say much, because that animal may have come from a nest a kilometre away. What really helps is a nest that has been found.
And that is the problem. In summer a secondary nest hangs hidden among the leaves, ten to fifteen metres up, and usually only becomes visible after the leaves fall in October or November. By then the young queens have already flown out and the nest has done its work.
So beekeepers and volunteers track nests down during the season itself, using a method that is surprisingly simple: a jam jar, a strip of cloth, a bottle of beer and a watch. This article explains how it works, step by step.
First this: what you are and are not doing
A wick jar is often confused with a trap, and it is not one.
- A wick jar does not catch and does not kill. The wick sticks through the lid so a hornet can reach the bait without drowning in it. That is the whole point: you need a live animal that flies back to the nest.
- The aim is direction and distance, not numbers. You want to know where the nest hangs.
- You will never deal with that nest yourself. That is work for a specialist firm, and the reason is further down.
Kill traps with open liquid do the opposite of what you want. They mostly catch hoverflies, wasps, butterflies and beetles, and the handful of hornets that drown in them can no longer tell you anything.
When it works, and when it does not
The method rests on one thing: that a hornet fancies sugar. That changes through the season.
- May to July · the best period. Workers are gathering carbohydrates for themselves and come to the jar readily. In spring this is also how you find primary nests, which are still small and hang low.
- From August · harder. The nest is then full of larvae and the workers hunt mainly for protein, so for meat and for bees. They respond less to a sweet jar. In this period, watching at your own apiary is often more effective.
- Weather · calm, dry and sunny. In strong wind or rain they fly little and your flight times stop meaning anything.
What you need
- A glass jar with a screw lid · an empty honey jar is ideal
- A piece of cotton or a cloth for the wick
- A nail or bradawl to make a hole in the lid
- Blond beer, white wine and sugar · or ready-made wasp lure
- Paint markers in a few colours
- A marking tube with a soft plunger
- A watch or the stopwatch on your phone
- A compass · your phone has one
- A map or a map app you can draw on
All together that is an hour of work and a few euros.
Step 1 · Making the wick jar
Make a hole in the lid with a nail, just big enough to pull the cloth through. Pull the wick far enough that it reaches the bottom of the jar and sticks out two to three centimetres at the top.
Fill the jar halfway with bait and screw the lid on. The liquid rises into the wick by itself. The hornet drinks from the wet tip and never touches the liquid.
A jar with a wide lid works better than a narrow bottle: the animal has to be able to land somewhere.
Step 2 · The bait
The basic recipe is equal parts:
1.blond beer
2.white wine
3.sugar
So one third each. A common variant replaces the sugar with grenadine, which seems to work a little faster. Ready-made wasp lure such as Trappit works well too and saves the bother.
Why beer and wine? Because it ferments and is slightly alcoholic. That is exactly what draws hornets and wasps, while honey bees are barely interested. So you attract your target and not your own colony.
And for the same reason: do not use honey as bait. Two reasons, both serious. You will attract your own bees instead of hornets. And open honey of unknown origin is the classic way to spread .
Step 3 · Where to hang it
Hang the jar at shoulder height, in an open, sunny spot you can see from three sides. You need to be able to see which way an animal flies off, and that will not work if there is a fence or a hedge in the way.
Good spots are near plants hornets already visit:
- Cotoneaster · June and July
- Snowberry · all summer
- Ivy · in autumn, when little else is in flower
- Fruit trees and windfall · August and September
- Your own apiary · if you see hunting at the
Do not hang it next to a terrace, a sandpit or a path. You want to draw hornets to a place where you can stand and watch quietly, not to the garden where the grandchildren play.
Be patient. Sometimes one turns up within half an hour, sometimes it takes two days. Top the jar up when it runs low or the bait dries out.
Step 4 · Marking hornets
This is the step most people skip, and precisely the step that separates measuring from guessing.
Without a mark you do not know whether the hornet returning after three minutes is the one that flew off. It might be a second animal from the same nest, or from a completely different one. Your flight time is then worthless.
How to do it:
1.Put the marking tube carefully over the animal while it drinks
2.Push the plunger until the hornet cannot turn, and no further
3.Put a dot on the thorax with a paint marker
4.Let the paint dry for half a minute
5.Let the animal walk out onto the jar
Use a different colour per hornet, so you can follow several at once. Work calmly, without jolts. A hornet at the jar is busy eating and will only sting if it feels trapped.
Step 5 · Measuring
From now on you watch two things.
The flight direction. See where the animal disappears and take your compass. Write the direction down in degrees, not as "that way". Over a few hundred metres, ten degrees already makes tens of metres of difference.
The flight time. Start your stopwatch the moment the animal leaves and stop it as soon as it is back on the jar. That time covers the outward flight, unloading at the nest, and the return.
The rule of thumb used everywhere:
One minute of flight time corresponds to roughly one hundred metres to the nest.
So three minutes is roughly three hundred metres. It is a rule of thumb and not a measurement: a headwind, a detour around a wood, or an animal that stops on the way all make the time longer. Which is why:
- Take at least five measurements per marked animal
- Use the shortest reliable time, because any interruption only makes it longer
- Say "between 200 and 400 metres" rather than a precise figure you are going to trust
Step 6 · Triangulating
Now it becomes geometry. Draw a line on a map from your jar in the measured direction, and mark a circle at the estimated distance.
Then move the jar a few hundred metres, preferably across that line, and do it again. Where the two directions cross is where the nest hangs. With a third point you can be fairly certain. That is triangulation, the same principle by which two bearings place a ship at sea.
A second approach is the relay method: you move the jar a hundred to two hundred metres at a time in the direction you found, and measure again. The flight time gets shorter as you close in. Under a minute means the nest is within a hundred metres.
From that point on, look up instead of at your jar. Search for the flight line against the sky, best with a low sun behind you. Binoculars help enormously. Nests are often high in a tree, but also in a hedge, under a roof edge or in a shed.
Step 7 · Reporting and registering
If you have found a nest, or even have a strong suspicion, report it. Do nothing yourself, and do not climb up to make sure.
In the Netherlands
Report through waarneming.nl/go/vespa-velutina. That is where it belongs: EIS Kenniscentrum Insecten assesses the report and passes it to the province. You can report without an account.
Include:
- A photo, even a blurred one
- The location as precisely as you can · a pin on the map beats a street name
- The height and what the nest is sitting in, if you can see it
- Your own contact details, so someone can call you back
Bear in mind that a report does not automatically mean the nest will be removed. Policy narrowed in 2026: provinces now mainly have nests removed that pose a concrete risk, and who pays and who carries it out differs by province and municipality. Check your province or municipality website for what applies there. Your report still counts if the nest stays put, because without reports nobody knows where the species is.
In Belgium
Report through vespawatch.be, which feeds into waarnemingen.be. Follow-up there runs through accredited controllers.
Join a search group
In more and more regions there are groups of beekeepers and volunteers doing this together. They already have the marking tubes, they know the area and they have last year's measurements. One afternoon with them teaches you more than this whole article. Ask your beekeeping association.
What not to do
- Deal with a nest yourself. A disturbed nest activates hundreds of animals at once, they can sting repeatedly and they will follow you a long way. Most accidents happen with nests that hang low and look harmless.
- Spray water at it, put a bag over it, get a ladder. Every year this goes wrong somewhere.
- Set kill traps with open liquid. The bycatch of hoverflies and butterflies is large and it gets you nothing.
- Use honey as bait. See above.
- Measure on someone else's land without asking. You will be standing there peering at a tree through binoculars; ringing the doorbell saves an awkward conversation.
Frequently asked questions
How long before a hornet turns up at the wick jar?
It varies a lot. In a good spot in June one sometimes arrives within half an hour. In the wrong spot it can take days. Leave the jar in place and keep it topped up; only move it after a day or two if nothing comes.
Does the method work with only one jar?
Partly. With one jar you get a direction and an estimate of the distance, and that is already valuable in a report. For a real fix on the location you need a second and preferably third measuring point, or you move the same jar along the direction you found.
Will a wick jar draw extra hornets to my apiary?
You attract what is already there. A wick jar does not pull hornets in from another area; it makes visible what is flying around nearby. If you would rather keep some distance, hang it a few dozen metres from your hives.
Am I allowed to catch and mark a hornet?
The Asian hornet is on the European list of invasive alien species and is not protected. Marking and releasing for research and tracking is standard practice in search groups. Do make sure you know which species you have in front of you: the European hornet is protected and may not be caught or killed.
What if I find the nest but nobody removes it?
That can happen, certainly now that provinces only have nests removed that pose a concrete risk. Your report is still useful, because it helps build the picture of the spread. If the nest is on your own land and you want it gone anyway, you can hire a specialist; reckon on ninety to two hundred euros depending on height and access.
Can I use a camera or a drone for this?
have been tried for following flight lines, with mixed success. For most people binoculars and patience are more practical. In any case, never fly a drone at a nest: that is dangerous for the aircraft and for everyone underneath it.
In closing
Tracking is a skill, not a trick. The first time takes an afternoon and may turn up nothing. The second time you know what to look for, and the third time you are suddenly standing under a tree with a nest in it.
The good part is that the kit is nothing special. A jam jar, a strip of cloth and the willingness to stand still and watch for an hour. That is enough to find something that is unfindable from a car or from behind a desk.
If you want to know how to recognise the Asian hornet and tell it from the European one, read our article on recognising and reporting first. What it does to your colonies and how to protect your hives is in the article for beekeepers.
Have you tracked one down yourself, or are you stuck somewhere? Share it on the forum under Bijengezondheid & Ziekten. Measurements from different corners of the country are exactly what makes this approach better.