The Asian hornet arrived in France in 2004 and has become the scourge of all amateur beekeepers. From the beginning of August, Frédéric Wielezynski, a beekeeper in the Médoc region of France, spends every weekend tirelessly repeating the same futile gestures. He positions himself in front of his hives armed with a fly swat and tries to crush the enormous bee-eating hornets. These are not just any hornets, but the Asian Vespa velutina. "I know it's useless, because a dozen more will arrive as soon as my back is turned, but I have to do something," said Wielezynski, president of the Gironde and Aquitaine beekeepers' association. "I love my bees and I can't just stand by and see them being eaten up without doing anything about it."

The attacks are quite impressive. Groups of five or 10 hornets hover in front of a hive waiting for the return of the forager bees. "It's like a barbarian invasion, they destroy everything in their path," said Richard Legrand, vice-president of the beekeepers association in Dordogne, one of the worst-hit departments in France. Once the Vespa velutina has got hold of its prey, it attaches itself to a branch and begins its sinister dismantling of the bee. First the head falls to the ground, then the wings and the legs. The hornet keeps only the protein-rich thorax, which it carries back to its nest for the hungry larvae.

From September, when there are fewer bees guarding the hives, the hornets even enter them and eat the brood. In any case, by then the bees are too frightened to go out. It's a vicious circle, according to Wielezynski. "If they don't go out there's less food and water in the hive, so the queen stops laying eggs and the bee population grows weaker and older. Then it's far more likely to die before the onset of winter."

The Asian hornets – distinguished by their yellow feet – first appeared in Tonneins in the Lot-et-Garonne department of south-west France in 2004. They probably started with a few queens hibernating in some Chinese pottery imported by a local bonsai producer. "We're almost certain that they are from China, probably a province near Shanghai," said Claire Villemant, entomologist at the Natural History Museum and co-ordinator of a research project financed by the European Apiculture Programme.

The results of the research published by the museum last June show how the insect has spread from three nests recorded in 2004 in a single department to nearly 2,000 in 2010 across 39 departments. Two nests have recently been reported in Spain for the first time. "Every year they spread by some 100km, with a very large presence in Aquitaine, where the climate is as good as in their original habitat in China, if not better," observed Quentin Rome, a researcher at the Natural History Museum. According to the study, the hornet is likely to acclimatise in most European countries, especially along the Atlantic coast and the northern Mediterranean. Eastern Europe and Turkey may also be overrun in the future.

Yet the Asian hornet has not been classified as a pest. It causes considerable damage to amateur beekeepers, but the professional ones, who account for 60% of France's honey production, have been spared overall.

There is also the matter of stings. In the Médoc region last June a 50-year-old woman died from Asian hornet stings. Nevertheless there does not appear to be any specific public health problem and hospitals in Agen, Bergerac and Bordeaux, near the regions with the highest hornet populations, have not observed an increase in cases. "Vespa velutina is not usually aggressive when alone, but is potentially dangerous and may attack if it feels threatened and is with its fellow hornets," explained Denis Thiery, head of a research programme in Bordeaux's National Institute of Agronomic Research (INRA). His unit has been working on ways to trap the hornet.

To date no entirely reliable technique has been found."In any case, we've got to be realistic," said Villemant. "That species is now part of our own, so we're going to have to learn to live with it."

This article originally appeared in Le Monde