78 km per year: the expansion rate of Asian hornet in France

Key takeaways

Key figure: 78 km per year is the average rate of progression of the Asian hornet's invasion front in France since its arrival in 2004, according to studies by the MNHN and INRAE.

Facts to know:

• 2004: arrival in Lot-et-Garonne via pottery imported from China
• 2009: 32 departments colonized (5 years after arrival)
• 2025: more than 90 departments affected, present in Corsica since August 2024
• Today: progression continues at a rate of 60 to 80 km per year

Why this speed: a single queen can produce 500 to 1000 future queens per year, which disperse in all directions the following spring. In addition, accidental transport by vehicles, goods, and boats creates unpredictable geographical "jumps".

The starting point: a cargo accident in 2004

The story begins in an unlikely place: the property of a horticulturist in Lot-et-Garonne, near Agen. In spring 2004, in a shipment of pottery from Yixing, in the Shanghai region, a few queen Vespa velutina nigrithorax traveled to France, probably hidden in the crevices of the ceramics.

Spring is the ideal time for invasion: it is precisely when queens emerge from hibernation and look for a place to found their nest. They only had to do what they are programmed for: lay eggs, raise workers, expand a colony. A few months later, the first French nest was established.

The horticulturist noticed the insect's presence as early as 2004, but it was only in 2006 that naturalists Jean Haxaire and his colleagues officially identified the species and published the first description in the scientific journal Bulletin de la Société entomologique de France. By this date, the Asian hornet was already established in 13 departments of the Southwest.

The scenario that followed is that of a classic biological invasion, but one of exceptional rapidity.

How is invasion speed measured?

The figure of 78 km per year is not a slogan: it is a scientific average calculated by researchers from the MNHN (Quentin Rome, Claire Villemant) and INRAE (Christelle Robinet) using a rigorous method.

Since 2007, national monitoring has been carried out by the National Inventory of Natural Heritage (INPN) through a participatory science program. Each reported nest or individual is geolocated and integrated into a cartographic database. By cross-referencing these reports year by year, researchers can trace the invasion front — the advanced line where the species has just established itself — and measure its geographical displacement.

Studies published in 2015 (Rome et al.) and 2017 (Robinet et al.) established an average annual progression of 78 km, with peaks observed in certain years (up to 100 km in favorable conditions) and slowdowns (mountainous areas, cold climates).

Today, recent estimates place the progression between 60 and 80 km per year — a slight slowdown explained by the gradual saturation of metropolitan territory. When there are not many uncolonized areas left, mechanically, the speed of "conquest" decreases.

Why such a rapid spread?

78 km per year is enormous for an insect. By comparison, most invasive species progress a few kilometers per year. The Asian hornet is among the all-time champions of biological invasion. Three main factors explain this rapidity.

Factor 1: Explosive reproduction

A single mature Asian hornet nest produces, at the end of the season, 500 to 1000 future queens, sometimes more. Each of these queens, after hibernation, is capable of starting a new colony the following spring. Even if only a few percent survive and manage to found a viable nest, this represents several tens of new nests per year from a single initial nest.

This exponential multiplication is the primary cause of the territorial explosion.

Factor 2: Wide natural dispersion

After hibernation, young queens do not stay near the parental nest. They can fly for several tens of kilometers in search of a favorable location. This natural dispersion, combined with the massive production of queens, generates a continuous biological advance front, without geographical bottlenecks.

Factor 3: Anthropogenic "jumps"

This is the least known factor, but perhaps the most problematic. Queens readily hide in materials transported by humans: wooden pallets, cargo, caravans, containers, firewood logs, potted plants. These geographical "jumps" allow the species to appear suddenly hundreds of kilometers from the regular invasion front.

This explains the arrival of the Asian hornet in Corsica in August 2024, in England as early as 2016, or even in Northern Italy — all "jumps" that do not follow the logic of continuous progression.

The conquest timeline: 20 years in figures

To visualize the progression concretely, here are the major stages of the French and European colonization.

2004-2006: Discrete establishment

Presence limited to Lot-et-Garonne and neighboring departments (Dordogne, Landes, Gironde). Local naturalists began to observe the species without yet gauging its scale. End of 2006: 13 departments colonized.

2007-2010: Regional expansion

The hornet spread throughout the Southwest, then moved north to the Center and West. In 2009, 32 departments were affected. The first beekeeping alerts began to be heard. The species was classified as a "sanitary hazard" in 2012 under the rural code and an "invasive alien species" under the environmental code.

2010-2015: National conquest

Rapid progression towards the North, East, and Massif Central. First confirmed border crossing into Spain in 2010. Portugal followed in 2011, Belgium in 2011, Italy in 2012, the Netherlands in 2017.

2015-2020: European extension

All departments of mainland France are now affected or in the process of being so. England detected its first nests in 2016. Germany and Switzerland reported their first observations. The European scientific network was structured to coordinate monitoring.

2020-2025: Saturation and jumps

Mainland France is fully colonized. The newly conquered territories are now islands or distant areas: Corsica in August 2024, intensification in England, confirmed presence in Ireland. The rate of national progression stabilizes around 60-80 km per year, but the species continues to "densify" its presence in already colonized territories.

Where are we today?

In 2025, the observation is clear: more than 90 French departments are affected, and the species is present in a dozen European countries. However, there are a few important nuances.

The most affected areas

The Southwest remains the historical area of highest density, with record numbers of nests reported in Aquitaine, Pays de la Loire, and Brittany. The density there is such that in some communes, several tens of nests are destroyed each season.

Less dense areas

Certain mountainous regions (Alps, Pyrenees, upper Massif Central) slow down expansion due to altitudes and harsh winters. But "less dense" does not mean "absent": progression continues every year.

Corsica, the last conquered territory

The arrival of the Asian hornet in Corsica in August 2024 marked a symbolic step. For 20 years, the island had been spared due to its maritime isolation. The hornet probably arrived by ferry, in a vehicle or goods. Its spread there is now very closely monitored by local authorities and the MNHN.

And beyond?

Expansion in Europe continues. Climate models predict a possible colonization of all temperate Europe by 2050, with the exception of the coldest areas (Scandinavia, Northern Russia). The future of the British Isles and Ireland, still in the early stages of invasion, will largely depend on the ability of authorities to coordinate massive and early surveillance.

What does this invasion speed teach us?

The figure of 78 km per year is not just a curious data point. It carries several major strategic lessons.

Lesson 1: Eradication is no longer possible

At this rate of expansion, and with 20 years of establishment, no eradication action on a national scale is currently conceivable. The fight is now about local regulation: targeted spring trapping, nest destruction, apiary protection. The objective is no longer "eliminate", but "contain and coexist".

Lesson 2: "Preserved areas" no longer exist

If you live in a region still considered "little affected," make no mistake. At the current rate, no metropolitan territory will remain spared in the long term. Anticipating its arrival, rather than suffering it, is the most profitable strategy.

Lesson 3: Spring trapping makes perfect sense

Faced with a species that produces 500 to 1000 queens per nest per year, each queen intercepted in spring has a disproportionate impact. It's mathematical: 1 queen captured in March-April means 1 nest avoided, and thus 500 to 1000 future queens who will never see the light of day the following year. At the departmental level, the cumulative effect is considerable.

Lesson 4: Citizen science is our best weapon

Invasion mapping only works thanks to reports from individuals. Every nest reported on official platforms (signalnids.fr, INPN Espèces, town halls) feeds the scientific database that helps understand and anticipate progression. This is probably one of the largest participatory science programs in France.

What can you do concretely?

Faced with such a dizzying figure, one can feel powerless. That is a mistake. On an individual level, every action counts.

Report everything you see

A nest, a hornet, suspicious behavior around a beehive: everything must be reported. Official platforms (signalnids.fr, INPN Espèces, your town hall) feed the national mapping. These reports are not trivial: they help identify at-risk areas, target interventions, and measure progression.

Trap selectively in spring

Between March and May, setting up a selective trap near your home can intercept one or more queens. Given the reproductive potential of the species, this is the most effective individual action. Beware: selective is the keyword. Non-selective homemade traps (cut bottles) capture 99% of auxiliary insects unnecessarily, which worsens the problem instead of solving it.

Protect your garden's pollinators

The more pollinators your garden attracts, the more the Asian hornet will identify it as a hunting ground. Combining biodiversity (nectar-rich flowers, insect shelters, water points) with selective trapping is the most coherent strategy.

Raise awareness around you

Neighbors, family, colleagues: many people are still unaware of the extent of the phenomenon or confuse Asian hornets with European hornets (which are useful and sometimes protected). Sharing verified information is also participating in the fight.

20 years after its arrival, the Asian hornet is now part of the French landscape. The question is no longer whether it will be present near you, but how you will prepare for it. On an individual level, every action counts. On a collective level, every report, every trap, every protected hive makes a difference.

Bzzz, see you soon, Buzette.

Do you want to act now against the progression of the Asian hornet near you? Discover Hornet EcoTrap, the selective trap made in France that intercepts queens in spring, where action is most effective in slowing the invasion.

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