- Two phenomena of exceptional precipitation in March, then at the end of April-beginning of May, recharged the wetlands of the metropolis with water, where the mosquito has developed considerably.
- In parallel, the tiger mosquito, which proliferates in the stagnant waters of our gardens, made its reappearance on May 2.
- The mosquito control center, which operates only in the public domain, reminds individuals of the good gestures to adopt to eradicate lodgings with tiger mosquito larvae.
"Mosquitoes swarm and make Bordeaux life a hell!" "Testimonies like that of Virginie, are increasing in Bordeaux in recent weeks. So much so that she decided to launch a petition to ask the town hall to "commit to eradicating the problem".
But it is not as simple as that, and above all, "everyone must be an actor in the fight against the proliferation of mosquitoes" insists Christophe Courtin, in charge of studies and coordination at the Bordeaux Métropole mosquito control center. Contacted by 20 Minutes , this specialist confirms that we are currently living in an "exceptional" situation in the agglomeration of Bordeaux, and even throughout the Gironde.
On May 10, 70 mm of rain fell, the equivalent of a month
"This is due to two exceptional weather episodes, which we only meet once every ten years," he explains. First, between 1 and 15 March, there was 100 mm of precipitation, which triggered mosquito hatching, particularly in the peripheral wetlands of Bordeaux Métropole. They produced mosquitoes which were a nuisance in the second half of March and the first half of April. Subsequently, we had a second rainy and stormy episode even more important, stalled between April 27 and especially May 10, since it fell more than 70 mm of rain that day, the equivalent of this that can be received in the space of a month, and which has resulted in the widespread re-watering throughout the Girondin territory of mosquito production sectors, especially in wetlands. "
A “massive” phenomenon, which occurred “in a period that was not conducive to intervention since we were in full confinement. The result was not expected with a massive presence of adult mosquitoes in areas near wetlands, and we are still suffering the consequences these days since the lifespan of a mosquito is one month , a month and a half. “In all, around fifteen municipalities in the metropolitan area are concerned, mainly on the Ambès peninsula, the south of the metropolis in Bègles and Villenave-d'Ornon, and also in Pessac, Mérignac, Saint-Aubin-du -Médoc, Le Taillan, Blanquefort or Parempuyre. "
"A very small amount of water is enough to be the site of hatching of tiger mosquito eggs"
These weather phenomena are responsible for the appearance of local mosquito species only. "At the same time," emphasizes the specialist, "the tiger mosquito also made its appearance, faithful to the meeting, from May 2. The tiger mosquito is strictly urban: it is the garden mosquito, produced by human activity. About 80% of tiger mosquito larvae are on private property. It is therefore up to everyone to make the right moves. "
The right actions are the elimination or good management of all the water points that can be found in a garden or in an enclosed space. “It is above all the rainwater collectors - which are real tiger mosquito factories - that must be made waterproof and cleaned regularly when possible. There are also the manholes of rainwater, which must be ensured the good flow. In the gardens, there are still many objects that can be removed or covered: tarpaulins where we find pockets of water formed in the folds, plastic garden tables, containers, watering cans , old tires ... A very small amount of water is enough to be the site of hatching of tiger mosquito eggs. We can obviously keep water points, for birds or for bees, but we must take care to renew this water every four to five days, which is the time of development of the larva. "
The mosquito control center also wishes to find solutions to act at the cemeteries of the metropolis, "which are large centers of production of tiger mosquitoes, because of the funeral vases which, when filled with water, shelter larvae. However, one cannot touch tombs which are private property. It is the same problem for the fifty shared gardens of the metropolis. "
"The tiger mosquito is a homebody, and is only 150 meters at most"
The ways of life of local mosquitoes and the tiger mosquito are very different. “There are sixteen different local mosquito species on the territory of Bordeaux Métropole, says Christophe Courtin, not all of them bite humans, but those that bite are capable from their point of emergence of making several hundred meters or even several kilometers. The tiger mosquito is a homebody, and is only 150 meters at most. "In addition," local mosquitoes have a preference for biting at the end of the afternoon or in the morning, the tiger is a daytime mosquito. Finally, we recognize very well the tiger, which is a very small mosquito, of the order of 5 mm, while the other conventional mosquitoes reach a centimeter. "
Created on January 1 by Bordeaux Métropole, the mosquito control center employs 11 agents who are dedicated to this activity in 27 municipalities. They are responsible for monitoring the environment and eliminating breeding places with bio-insecticides, only in the public domain. “Regulatory, we cannot intervene on private plots, specifies Christophe Courtin, and we act only within the framework of anti-larval control, because it is prohibited for our service to eradicate the adult mosquito, because of the products that would impact pollinating wildlife. "
Our mosquito record
Thanks to the drop in temperatures, the activity of the tiger mosquito has "calmed down a bit" in recent days, notes the mosquito control center. “We note that when temperatures drop, reports of tiger mosquitoes are much weaker, which has been the case since June 1 after the hot weather in May. But we know that it will start to rise again in July-August. It will then be up to everyone to keep a close watch on their areas of standing water in their garden.
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