What can an Asian hornet nest look like in the UK?

Picture yourself out in the garden on a crisp April morning, clearing out cobwebs in the shed or reaching up to tidy a neglected birdhouse under the eaves. Instead of dusty old flowerpots, you spot a strange, greyish-brown paper bulb dangling from the timber, roughly the size of a tennis ball. That is your first encounter with an Asian hornet nest. These early spring structures are built entirely by a single queen who survived the winter, and they are usually tucked away in low, sheltered spots. But if that same nest goes unnoticed, the story changes drastically by the time late summer rolls around.

What starts as a modest nursery turns into a bustling metropolis by August. The colony expands so quickly that the original space simply cannot hold thousands of hungry workers. Because of this, the hornets often abandon that first shed or porch location entirely and relocate to build a massive secondary nest.

You might wonder how a tiny paper ball swells into something the size of a basketball or even a large beach ball. The workers achieve this by chewing up raw wood fibers from fences or tree bark, mixing it with their saliva, and layering it into a tough, swirled paper envelope. Instead of staying down at eye level, most of these large secondary nests end up hidden high in tree canopies, often more than 10 meters above the ground, where leaves camouflage them completely until the autumn winds finally strip the branches bare.

Telling an Asian hornet nest apart from other garden wildlife usually depends on the season, the height, and the architecture. In spring, a small primary nest sits low to the ground, usually under 2 meters, and features a single entrance hole right at the bottom. By late summer, a secondary nest usually hangs high in a tree, looks spherical or egg-shaped, and characteristically features a side entrance hole rather than an opening at the bottom.

You cannot rely on the nest alone for a positive identification, though, because native wasps, paper wasps, and European hornets also build paper structures. You usually have to look at the insect itself. An Asian hornet worker measures about 20 to 25 millimeters long, featuring a dark brown or velvety black thorax and a distinct bright orange or yellow band on the fourth segment of its abdomen.

One detail that really stands out if you manage to get a close look is their legs. They sport dark upper segments that end in bright yellow lower parts, which makes it look like the hornet is wearing bright yellow socks. You might also notice their face, which is a striking orange-yellow. Be careful not to confuse them with the native European hornet, which is larger, redder, and has a different abdominal pattern. People also occasionally worry about massive giant hornets often sensationalized in the media, but that species is not present in the UK.

When you spot a suspected nest, your next move is simple: you leave it entirely alone. It feels tempting to grab a can of wasp spray or poke at a small spring nest with a broom handle, but self-treatment is genuinely hazardous. Disturbing the nest triggers immediate defensive behavior, and hornets can sting repeatedly. On top of that, a botched DIY attempt usually only kills a few workers while letting the queen slip away to rebuild nearby.

Instead of taking matters into your own hands, your best course of action is to capture photographic proof from a safe distance of at least 5 to 10 meters. Once you have a clear picture, you should report the sighting right away. In the UK, the quickest method is using the free Asian Hornet Watch mobile app, which lets you upload your photo along with your location straight to the authorities. You can also submit reports through the official online portal run by the Non-Native Species Secretariat.

Verification is essential because official eradication teams need positive confirmation before they deploy. Once the report is checked and verified, experts from the Animal and Plant Health Agency and the National Bee Unit step in to manage the removal safely using specialized protective gear and approved professional methods.

You need professional intervention the moment you suspect you have found an active Asian hornet nest, period. There is no safe DIY phase for dealing with these insects, especially once a colony reaches its summer peak and thousands of aggressive workers are on guard duty. If you notice a steady stream of dark, yellow-footed hornets hovering motionless right outside local beehive entrances in a predatory hunting pattern, or if you spot a straight flight line of foragers heading toward a dense tree line, a secondary nest is almost certainly nearby.

On the health and safety front, you should involve a clinician immediately if anyone is stung and shows signs of an allergic reaction, such as swelling of the throat, difficulty breathing, or dizziness. Even for people without a known allergy, multiple stings from defending hornets can deliver a heavy dose of venom that causes intense pain and localized tissue damage.

Leave the tracking, the verification, and the physical destruction of the nest entirely to the National Bee Unit and licensed pest control contractors. Your job stops at spotting the signs, keeping your distance, and passing the evidence along to the people equipped to handle it safely.