Chiggers, hornets, black flies… With climate change, get used to them

Insects, mites… They are affected by climate change, which forces migration and upsets their presence during the seasons. Soil artificialization, which deprives the habitat of many insects, forces interactions with human beings. “Global warming causes migrations of insects and animals that move in the cool, from region to region, which means that we discover species that we have never seen before”, indicates to West France Michel Collin, from the Brittany entomology study office.

Read also: Cochineal-tortoise: what is this insect pest that suffocates trees in the south of France?

Chiggers have migrated

This is the case of chiggers, these small red microscopic mites, which abound in mid-summer in the tall grasses of meadows and fields, especially vines, but also in poorly maintained lawns. “With global warming. They migrated and arrived in areas where we hadn’t had them before,” reports Michel Collin.

“The bites are painful and the reaction can last seven days”, explains the entomologist. “You walk in the tall grass, it goes up your body, then it comes to bite you because it feeds on blood like mosquitoes. We see it more frequently. People confuse these kinds of injuries with bed bugs. »

Ticks and Lyme disease

Another problematic mite is the tick. The rise in temperatures over a longer summer period, and a milder winter, promotes the development of ticks. “Climate change, by altering humidity and seasonal temperatures, allows tick populations to colonize habitats at higher altitudes”, remember the government. “The fragmentation of forests also promotes encounters between humans and ticks, which generally increases the risk of contamination. »

If these mites feed on blood primarily from animals, they can accidentally feed on humans, and potentially transmit bacteria that cause Lyme disease, which leads to around 800 hospitalizations in France each year, according to Public health France.

The tiger mosquito, even in winter?

Well known, the tiger mosquito has become acclimatized in France. “Global warming has enormously favored the proliferation of mosquitoes and in particular the tiger mosquito”, indicates Michel Collin, who explains that in the West his presence has been recorded to Nantes. “Stagnant waters are getting warmer and warmer, which promotes their upsurge. »

Originally from the tropical forests of Southeast Asia, the tiger mosquito has managed to adapt to various environments and climates, including many territories in France, explains the Regional Health Agency. In addition to the bite and its itching, the tiger mosquito can potentially carry diseases such as dengue fever, chikungunya or the zika virus, if the insect has already bitten an infected person – who, for example, has returned from a trip where circulate these viruses.

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According to the ministry of health, the tiger mosquito was first observed in the Alpes-Maritimes in 2004, before developing and gradually settling in the south of France and in Île-de-France. In January 2023, 71 departments were colonized by the tiger mosquito out of the 96 metropolitan departments. “For mosquitoes, we will have them all year round, and even in winter, we will not be safe from having mosquito bites”, comments Michel Collin.

Read also: The tiger mosquito is back, here are six reflexes to adopt to avoid being bitten

Hornets where you least expect them

According to the entomologist, hornets and wasps could show up more, including in the fall, with the impact of heat on the fruits. “Global warming will promote the putrefaction and decomposition of fruits, so everything that will be at market stalls and others will be invaded by this kind of insects which will come to feed on very ripe, sugar-rich fruits. », explains Michel Collin. “It’s dangerous for people handling the fruit. »

He also adds that the hornets could operate more at night, these insects do not like the heat. “If they couldn’t go out in these climatic conditions and the omnipresent heat, then they will go out at night, in the cool, because they need to feed. They have to acclimatize and adapt to different time zones,” continues the entomologist.

However, unlike the Asian hornet discovered in France in 2004, the European hornet is not a predator of bees and is not aggressive if its nest is not threatened. Although the bite of the Asian hornet is painful, the insect is no more dangerous for humans than its European cousin, except in cases of venom allergy. The bites can then be fatal.

Black flies at our doorstep

In Spain, the National Association of Environmental Health Societies (Anecpla) has warned against the proliferation of black flies, whose bites can cause severe pain or even an allergic reaction in some, with fever, itching, headache.

The black fly being fond of high temperatures, its proliferation would be due to the rise in temperatures which increases the metabolism of insects: “They breed for longer and more times,” explained Jorge Galván, director of Anecpla, who recommends avoiding waterways, at dawn and dusk, around which the insect swarms.

In France, the blackfly would be present since ” long time “, has however relativized Gérard Duvallet, medical and veterinary entomologist, professor emeritus at the Paul-Valéry University of Montpellier, quoted by The Parisian . He indicates that for the moment, there has been no case of sting identified in France.