Asian Hornet: Why October Is the Most Dangerous Month of 2026

Introduction: the season doesn't end when you think it does

In the minds of most gardeners, the danger from stinging insects belongs to July and August: patios, barbecues, wasps in a glass of rosé. Pest control professionals, on the other hand, look at their October schedule with a very different kind of concern. Because the Asian hornet (Vespa velutina nigrithorax) doesn't follow the holiday calendar: its colony reaches its maximum population between late September and early November, at a point when nests often hold 1,000 to 2,000 individuals, sometimes more in south-west France where the species has been established since 2004.

In other words: just as you're putting away the garden furniture, trimming the hedges and picking the last apples, the nest sitting ten metres above your head is at its peak. And it is busy manufacturing next year's infestation: several hundred future foundresses, which will mate and then disperse to overwinter.

This article isn't about the general biology of the Asian hornet, extensively documented by the Muséum national d'Histoire naturelle (which has coordinated reporting of the species since its arrival) and by INRAE. It is about a specific moment in the year — the six to eight weeks of autumn — and what that moment changes for a private individual: what they see, what they risk, what they should do and, above all, what they should not do.

What is actually happening inside a nest in October

The population peak

The cycle is annual and closes each winter. A foundress emerges from diapause in February or March, builds a primary nest the size of a golf ball (often under some form of shelter: a lean-to, a shed, a roller shutter housing), then raises her first workers. From May-June onwards, the colony generally relocates to a secondary nest, much larger and frequently perched high up in a tree.

From June to September, growth is exponential. In October, the colony stops raising workers: it produces reproductives — males and future queens. Estimates published by INRAE and reproduced in departmental control plans point to 200 to 500 viable foundresses per mature nest, a figure that varies with the vigour of the colony and the food resources available.

Why aggression increases

The Asian hornet is not an aggressive insect in the sense that it would seek out contact. It is, however, extremely defensive around the nest, with a reaction zone that widens once the colony holds a brood of reproductives to protect. Field feedback from fire and rescue services, which still attend a share of reports, puts that zone at 3 to 5 metres in summer, and up to 10 metres in autumn for a large nest disturbed by vibration.

And vibrations are something we produce in abundance in October: hedge trimmers, chainsaws, leaf blowers, a ladder leaning against a trunk, knocking fruit down with a pole. The vast majority of serious accidents in France do not happen during a chance encounter, but during garden work carried out close to an unnoticed nest.

The autumn paradox: the nest finally becomes visible

This is the good news of the season. A secondary Asian hornet nest, in full foliage, is often invisible: hidden in the dense canopy of an oak, a plane tree or a lime, 10 to 20 metres up. The fall of the leaves, between mid-October and late November, reveals it all at once.

Recognising an Asian hornet nest

• Shape: spherical to ovoid, up to 60-80 cm across for the largest, sometimes "pear-shaped".
• Material: papier-mâché of wood fibres, beige to light brown, with a streaked appearance.
• Opening: a side entrance, low on the flank — the European hornet (Vespa crabro), by contrast, leaves a wide opening facing downwards.
• Location: high up in a tree in roughly 70% of cases, but also under eaves, in a thick hedge, an open garage, a compost bin or a log pile.

To inspect a canopy or a set of eaves without getting close, a pair of compact 10x42 binoculars is the autumn gardener's most useful tool: it lets you see the entrance hole, the traffic at the opening and the true size of the nest from a safe distance. Plenty of people climb a ladder to "get a closer look" — that is exactly the opposite of what you should do.

A nest found in winter should not be treated

A crucial and poorly understood point: a nest discovered in December, January or February is empty. The colony dies with the first sustained cold, the foundresses have left and overwinter individually in the soil, under bark, in a log pile or a stump. An Asian hornet nest is never reused the following year. Paying for a destruction in the depths of winter therefore has no public health value; removing the envelope is, at best, a cosmetic matter. The only legitimate case: a nest in a thoroughfare, where its fall could injure someone.

Regulatory status in 2026: who does what, who pays what

The Asian hornet is classified as an invasive alien species of Union concern (EU Regulation 1143/2014, listed in 2016) and, in France, as a category two health hazard for the honey bee (order of 26 December 2012). That category two classification has a very concrete practical consequence: the State does not organise compulsory destruction and does not fund intervention on private property.

In practice, in 2026:

• Nest on private land → destruction is the responsibility of the owner, or of the residents' management body if the nest is in a common area. Typical cost of an intervention by a pest control company: €90 to €250 depending on height and accessibility, more beyond 15 metres or where a cherry picker is needed.
• Nest on public land (street tree, park, school) → the local authority or the highways manager.
• Local support: many municipalities, groups of municipalities and some departmental councils pay a partial subsidy (often 30 to 50%, sometimes a flat €50 to €80) on presentation of the invoice. The rule is not national: call your town hall before arranging the work, because funding is almost always conditional on using an approved company.
• Fire service: they no longer attend as a matter of course, except in emergencies with a person at risk (nest in a school, immediately next to an allergic individual, on the public highway).

For reporting, the reference platform remains frelonasiatique.mnhn.fr (Muséum national d'Histoire naturelle); several regions additionally run their own portals via FREDON and the GDS (animal health protection groups).

Bear in mind: no legal obligation requires you to destroy an Asian hornet nest on your own property. But the French Civil Code (article 1240, liability for things in one's keeping) may be invoked if a third party is stung because of a known nest left in place on your land.

What you must never do yourself

This is the most important part of this article, because the accidents recorded every autumn are depressingly consistent.

1. Never use an off-the-shelf aerosol on a secondary nest up high. "Wasp and hornet" sprays have a range of 4 to 6 metres, which is not enough, and using them triggers a mass emergence of workers. Hospital admissions for multiple stings almost always follow this scenario.
2. Never burn a nest. Risk of fire, risk of falling, and zero effectiveness: the envelope burns, the colony scatters.
3. Never shoot at it. Still seen in rural areas, this is dangerous and illegal, and leaves a torn-open nest and a furious colony on the ground.
4. Never block the entrance. The hornets get out elsewhere, and the colony becomes uncontrollable.
5. Don't climb. Any work at height on an active nest is a job for a professional equipped with a certified anti-hornet suit (standard beekeeping outfits offer no protection: the Asian hornet's sting is around 6 mm long and goes straight through thin fabric) and a telescopic injection pole.

The only case where personal action is up for discussion: a primary spring nest, the size of a golf ball, with the foundress alone and no workers, under an easily reachable shelter at ground level. And even then, a few days of observation is worth more than a hasty move.

Stings: what medicine says

An Asian hornet sting is painful but no more toxic than that of the European hornet at an equivalent dose. According to the factsheets from ANSES and Vidal, the real danger rests on two situations:

• Multiple stings (more than around twenty in an adult, fewer in a child), which trigger a systemic toxic reaction.
• An allergic reaction in a sensitised person, with a risk of anaphylactic shock within minutes — regardless of the number of stings.

Immediate action to take, as set out by Ameli and the poison control centres:

• Move away quickly on foot, without flailing; take shelter in a building or a vehicle.
• Remove rings and bracelets before swelling sets in.
• Disinfect and apply cold. A venom extractor or sting remover has no demonstrated benefit with hymenoptera, contrary to popular belief.
• Call 15 (the French emergency medical number) in the event of a sting in the mouth or throat, multiple stings, swelling of the face, breathing difficulty, faintness or widespread hives.
• Anyone already diagnosed as allergic should keep their adrenaline auto-injector within reach throughout the season, October included, and check its expiry date before autumn.

For simple stings with no history of reaction, a soothing after-bite cream based on dexpanthenol or a local antihistamine gel is generally enough, with the area monitored for 48 hours. Any spreading redness, heat and delayed fever points to a secondary infection and warrants medical advice.

Protecting your hives and garden at the end of the season

For beekeepers, October is a pivotal month: hornets hover in front of the hives, catch foragers and cause a flight blockage — the bees no longer dare to go out, the colony weakens before winter and may not make it through the cold months.

The measures endorsed by the beekeeping GDS and ITSAP remain mechanical above all:

• Reducing entrances and fitting an anti-hornet hive muzzle on exposed hives.
• Raising hives off the ground and using mesh floors to limit catches at ground level.
• Tracking the hornets' flight line to locate the nest: the insects return in a straight line, and triangulation with two observers often gives a useful bearing.

In the ornamental garden, a few simple habits sharply reduce attraction in autumn: pick up fallen fruit (apples, pears, figs, grapes — genuine sugary filling stations at the end of the season), cover the compost bin, rinse cans and bottles before putting them out for recycling, and postpone trimming dense hedges until you have checked there is no nest. To eat outdoors in early October, a simple insect-proof food cover placed over the dishes does more than any trap.

Trapping: a question of timing, not equipment

A contentious subject. ANSES, in its opinions on control methods against Vespa velutina, stresses the poor selectivity of commercial sweet-bait traps: they catch large numbers of non-target insects (native wasps, flies, moths, beetles) for a demonstrated effect on population dynamics that is very limited.

The current consensus among people working in the field:

• Autumn trapping around apiaries: accepted on a case-by-case basis, as a supplement to mechanical protection, never on its own.
• Generalised mass trapping: not recommended, counterproductive for biodiversity.
• Spring trapping of foundresses (February-April): this is the genuinely worthwhile window, because every foundress caught is a potential nest removed. Provided you use a selective trap with an exit for small insects and empty it regularly.

In other words, autumn mainly serves to prepare for spring: spot the nests as the leaves fall, note the locations, and schedule selective trapping from the first February days at 13-15 °C. It's the winter work that buys you a peaceful summer.

Action plan for the next six weeks

1. This week: walk the plot with binoculars, looking upwards. Check the eaves, sheds, shutter housings and log piles.
2. Before any pruning or chainsaw work: watch the hedge or tree in question for 5 minutes. Steady traffic of brown-black insects with yellow legs = stop work immediately.
3. If an active nest is confirmed: don't go near it, cordon off the area, keep children and pets away, call the town hall to find out about any available funding, then a company certified Certibiocide. An intervention is ideally carried out at dusk or dawn, when the whole colony is back inside.
4. Report the nest on the MNHN platform, even after destruction: the national mapping depends on it.
5. Note the location for February: an area that hosted a nest in 2026 is statistically more exposed in 2027.

For nests high up, in a shared hedge or in a multi-occupancy building, an assessment by a technician remains the surest way to know whether you are dealing with an Asian hornet, a European hornet or a wasp nest — three situations, three levels of urgency, three price brackets. Our intervention services cover detection and safe destruction, and our shop brings together the protective and preventive equipment that proves useful at the end of the season.

Sources

• Muséum national d'Histoire naturelle — national reporting platform for Vespa velutina
• INRAE — research on colony dynamics and the production of reproductives
• ANSES — opinions on control methods and trapping of Vespa velutina nigrithorax
• Order of 26 December 2012 (category two health hazard for the honey bee)
• Regulation (EU) No 1143/2014 on invasive alien species
• Ameli and Vidal — what to do in the event of a hymenoptera sting
• ITSAP – Institut de l'abeille — protecting apiaries against the Asian hornet