The proliferation of mosquitoes in the swamp

Bruno Garcia from the Charente-Maritime fishing federation answers questions from listeners on France Bleu la Rochelle, a question today from Claude who lives in Saint Thomas de Conac. Every night he has insects in his house that look like big mosquitoes. Does the proximity of the marsh have an influence on the proliferation of these insects? Saint Thomas de Conac, where is this town located?

Bruno Garcia: We are in the marshes of Gironde with the Saint Thomacais and Thomacaise. Sector where Cognac is produced, fine woods. About thirty km from Jonzac and about as much from Blaye.

The brandy! We guess your bearings! We come back to Claude’s mosquitoes.

These are not Claude mosquitoes but an insect that is commonly called “the cousin”. The real name is crane fly, we say a crane fly besides it is feminine and like flies it belongs to the Diptera family.

Why do we call him cousin?

Quite simply because it could be the cousin of the mosquito, it looks like one but fortunately it does not feed in the same way and above all it does not bite. I think we can say that it is a harmless animal but which would nevertheless have a small inconvenience. It lays eggs in the ground and its larvae buried under the ground would have the unpleasant inconvenience of degrading the roots of plants by digging galleries.

So nothing to do with the marshes near Claude’s?

As much as the mosquito reproduces in a liquid medium, the cousin reproduces on land. It indeed needs a humid and temperate environment to develop and that explains why in wet years we are spoiled with high populations of leatherjackets. This is not the case in very dry years. We can take for example this year 2022 with an overwhelming drought we see much fewer cousins ​​than in previous years. Despite everything for a few days and these few rainy episodes, you light up the veranda in the evening and they will not be long in coming to spin around the lamp, you will also enjoy them in the middle of your TV screen or quite simply at the end of your nose on the computer screen.

All of this is a bearable nuisance, must this cousin have an interest in nature?

Of course it is a very interesting food potential for birds, batrachians and fish. Indeed, the only means of defense and very original is their limbs which are brittle. When you want to grab it, a small filament remains between your fingers and the creature flies away as if nothing had happened. The legs benefit from breakage zones which, once broken, do not handicap them but do not grow back either and obviously as they only have 6 legs it cannot last forever.

What’s amazing is how quickly it gets invasive. Often from one day to another we find ourselves in the middle of a cloud of cousins ​​whereas the day before we did not see them.

As from one day to another they can disappear. this is explained by a high reproductive capacity, a female gives birth to at least 300 young. But the other reason is a very short life expectancy. Some just take the time to reproduce and don’t even allow themselves a moment to eat.


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