A pest controller is urging people to destroy Asian hornet nests this winter to prevent any hornets sheltering there from becoming queens next year.
Scientists have previously said that Asian hornet nests lie empty in winter, with next year’s queens leaving the nest to over-winter under bark or in attics.
These ‘future queens’ were thought to hibernate there until warmer weather in March, when they become active again, making a small nest in which to lay eggs for a new colony.
All other hornets were thought to leave the nest in winter, and die from starvation or the cold.
“But I have found lots of hornets hibernating in nests in winter,” pest controller Aurélien Castandet of Frelons et Cie, in Montendre, Charente Maritime, told The Connexion.
“From my own experience and from talking to other pest controllers, I estimate that of every 500 hornets that stay in nests over-winter, around 50 are still alive in March.”
In a video posted on YouTube, he shows a nest he destroyed in mid-October which still had many hornets in it.
Asian hornets are killed by extreme cold at around -40C, and when temperatures drop to -10C they enter a state of deep hibernation, said Mr Castandet.
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“We are a long way from seeing those sort of winter temperatures in this part of France,” he said.
The Asian hornetBilkis Akther/Shutterstock
Mr Castandet’s experience explains a story published in Charente Libre newspaper a decade ago, where a son-in-law who liked home crafts used an Asian hornet nest he found in a tree to make a table lamp as a Christmas present for his in-laws.
He made the gift in his cold workshop. It was only when he was with the whole family in a warm lounge at Christmas that there was suddenly an ominous buzzing and around a dozen angry hornets flew out of the ‘nest’ lamp.
Mr Castandet, who is a certified pest controller, said the cost of destroying an Asian hornet nest varied, but was usually around €100.
“It depends on the distance I have to travel and, above all, where it is located,” he said.
He usually destroys around 200 nests a year.
“If the nest is high up in a dense tree, or if it means I have to get up on roofs, it takes more time and effort and so costs more than one which is plainly visible in a tree and easy to get to.”
To destroy the nest, he uses a lance to punch a hole in it and then sprays in a pyrethrin-based insecticide powder.
You can find special aerosol ‘bombes’ to attack nests in most DIY stores for around €15.
They have a very powerful fogging jet with a range of 8m, that kills the hornets with a freezing cold jet of insecticide.
The aerosols should only be used at night, when most hornets are in the nest, and it is advisable to take all food away from the area. Anyone using one of these bombes should wear several layers of clothing, because Asian hornet stings can be half a centimetre long and able to penetrate even thick leather jackets.
Pest controller Aurélien CastandetFrelon & cie
But Mr Castandet recommends the safest solution is to go to a professional.
“The bombes can be effective and kill all the hornets if the nest is no bigger than a grapefruit, which is the size they usually are by late May,” he said.
“Any bigger, and you risk not killing all the hornets. As well as the obvious danger of them stinging you, any escapees will disperse and set up new nests, meaning you might well end up with more nests than you started with.”
There are a few municipalities which offer grants to help towards the cost of destroying nests, such as Rochefort in Charente Maritime, but they are few and far between.
Another method is to hang up traps aimed specifically at Asian hornets, which are widely available in France. Beekeepers, who are affected by Asian hornets attacking their hives, are starting to organise co-ordinated programmes using these traps in spring, saying it is the most effective form of pest control.
