Asian hornet: the growing risk of underground nests in gardens

For a long time, this dangerous wasp species was treated as an issue high up in tree canopies or tucked beneath roof eaves. Now the danger is shifting-quite literally-to the ground beneath our feet. Specialists who work with Asian hornet traps are reporting buried nests that go unnoticed until a lawnmower, a child or a dog disturbs them by accident.

When the hornet nest suddenly sits beneath the lawn

Since the mid-2000s, the yellow-legged Asian hornet has spread rapidly across large parts of Western Europe. It is best known for building large, conspicuous nests high in trees. That familiar image is exactly what misleads many people.

Local guidance leaflets and national action plans now make the point very clearly: nests can also be found

• in hedges
• in old tree stumps
• beneath shrubs
• in cracks in walls
• and directly in the soil.

A nest in the ground is easy to miss. There is no big, papery sphere and no clearly visible “flight path” at eye level. People walk past it, mow the grass, trim the hedge-and only at the moment of contact does the situation escalate.

"The real issue is not the number of underground nests, but the element of surprise in familiar surroundings."

At home in their own garden, many people feel safe and pay less attention to insect activity. That lowered vigilance is what makes buried hornet nests particularly risky.

Why underground nests react so unpredictably

The Asian hornet is not regarded as permanently aggressive. As a rule, it only attacks people when it believes its nest is under threat. With a hidden underground nest, however, even a minor vibration can be enough.

Typical triggers highlighted by professionals include:

• a lawnmower or robotic mower passing directly over the nest
• a petrol-powered strimmer used close to the ground
• hedge trimmers used on a concealed trunk section with a hollow
• children stamping or jumping near the nest
• dogs digging into the soil.

Safety guidance recommends keeping at least five metres away from a nest. With a ground nest, that is often simply not possible-because you do not spot it in advance.

"One careless step can mobilise an entire team of workers-without any warning at all."

For people, that means multiple stings in a very short time are realistic, particularly on the legs, arms and face. For allergy sufferers, children and older people, this can become life-threatening.

A hard hit for beekeepers: hornets in front of hives

The consequences for beekeeping and native insect life are at least as serious. The Asian hornet hunts honey bees in particular. It waits at hive entrances and snatches returning foragers in mid-air.

Beekeepers and specialist authorities report several effects:

• fewer foraging bees leaving the hive
• sustained, severe stress on the colony
• a drop in honey stores
• weakened colonies going into winter
• in extreme cases, the collapse of entire colonies.

On top of that, the hornet is an invasive species. It can put pressure not only on honey bees but also on native wild bees, hoverflies and other beneficial insects. That threatens ecosystems already struggling with pesticides, land sealing and climate-related stress.

"Every additional enemy of pollinators intensifies an equilibrium that has already become fragile."

Anyone who wants to protect bees, fruit trees and wild plants needs to take the hornet’s new role seriously-not only as a human health issue, but as an environmental factor.

What experts advise: stay calm and respond correctly

Despite growing concern, specialists warn against panic-driven actions. The most common mistake is trying to destroy a nest without help-using sprays, fire, water or stones.

Current advice is unambiguous:

• do not attempt to destroy the nest yourself
• keep your distance and avoid the area
• mark or cordon off the site, for example with barrier tape
• contact the local council, fire service or a specialist pest control company
• do not use loud or vibrating equipment near the nest.

The reason is straightforward: if an underground nest is disturbed, there may be no time to retreat calmly. By the time you realise what is happening, the first hornets are often already airborne.

"It is better to spot the clues early: unusually high numbers of hornets flying low to the ground, obvious flight routes to a hole in the soil, activity around an old stump."

Anyone who recognises these signs can move to safety in good time and arrange professional support. Many councils are increasingly setting up reporting systems for this-ranging from hotlines and online forms to maps showing confirmed nests.

Learning to live with a long-term problem

In many parts of Europe, authorities assume the Asian hornet is now established across wide areas. The idea of eradicating it quickly is seen as unrealistic. Control and monitoring require substantial funding and staff, often over many years.

As a result, the approach is changing: less focus on the ambition of complete removal, and more emphasis on slowing spread and reducing risk. This also means awareness cannot be treated as a late-summer issue that flares up briefly and then disappears again.

In the warmer months, lightly used spaces-overgrown garden corners, embankments, old woodpiles-should be entered regularly with a watchful eye. If you notice hornet movement patterns there, it is usually better to take a photograph from a safe distance and seek advice than to intervene yourself.

Practical tips for garden owners and families

Take a quick look before mowing

A simple check can significantly reduce risk. Before starting the lawnmower, it is worth taking a slow walk around the property:

• Are there spots where a lot of large insects are flying low?
• Can you see a hole in the ground with insects repeatedly going in and out?
• Does an old tree stump suddenly look “active”?

These patterns do not automatically mean hornets, but they do merit attention. If you are unsure, local wildlife groups or beekeeping associations can often point you towards knowledgeable contacts.

Explain simple rules to children and dog owners

Families should make children who are playing aware of the risk without frightening them. Clear, memorable rules can help:

• Do not put your hands into holes in the ground.
• Do not poke sticks into tree stumps.
• If you notice unusual insects, go straight to an adult.

Dog owners should try to prevent their pets from digging in natural areas during summer. A dog that charges straight into an underground nest can receive dozens of stings within seconds.

When to call emergency services-and why allergy sufferers must be extra careful

Guidance recommends calling the emergency services immediately after multiple stings, stings in the mouth or throat area, or any signs of an allergic reaction. These include, for example:

• a rash across the whole body
• sudden breathing difficulties
• dizziness, nausea, circulatory problems
• swelling of the face or neck.

People with a known insect-venom allergy should carry their emergency kit consistently throughout the hornet season-especially during gardening, walks and trips into the countryside.

At the same time, clinicians advise against staying indoors out of fear of hornets. Compared with everyday risks, the danger remains moderate as long as you stay alert and understand the typical hotspots.

Why traps alone will not solve the problem

Specialists who focus on traps for the Asian hornet warn against a false sense of security. Non-specific traps-such as those using sweet baits-often catch large numbers of other insects, including beneficial species. Their effect on hornets, by contrast, is limited.

Targeted traps can be useful near heavily affected apiaries, but they do not replace systematic nest searches or coordinated measures involving authorities, beekeepers and residents. Anyone experimenting in their own garden risks worsening the ecological problem without making a meaningful dent in hornet numbers.

The most effective approach remains a combination of measures: vigilant residents, well-informed councils, trained response teams-and a public that understands why an unremarkable hole in the ground can sometimes deserve more attention than a dramatic nest in a tree.