RAINSTORMS followed by warm weather are a perfect cocktail for an explosion of mosquitoes and tiger mosquitoes.
Today 20 departments in the regions Paca, Corse, Languedoc-Roussillon, Midi-Pyrénées, Aquitaine, Bourgogne and Rhône-Alpes are under surveillance for tiger mosquitoes, with checks in a further 32.
Mosquitoes need stagnant water for the growth of their eggs and the regional health authorities ARS remind householders they have a legal duty to clear stagnant water, even as far as emptying saucers under flowerpots at least once a week.
So far only around 10 localised cases are known of tiger mosquito bites leading to a disease such as chikungunya or dengue fever.
However, preventive measures are of little use once you wake to hear a mosquito buzzing at your ear – although as long as it is buzzing it is flying and not biting...
People always ask why they are the main targets while others are rarely bitten and University of Florida medical entomologist Dr Jonathan Day gave Time the answers – saying it is down to your genes and your “sweet skin” as granny would say.
Mosquitoes generally only live for about three weeks but in that time they are drawn to people whose genetic make-up gives a higher metabolic rate meaning their bodies release more carbon dioxide.
Genes also give your blood type and type O seems to attract mosquitoes more than A or B.
People’s skin also produces different chemicals and some “sweet skin” produces more lactic acid, that also attracts mossies.Only the females bite as they need blood after mating to produce their eggs and this means carbon dioxide is their main way of identifying targets as all vertebrates produce CO2.
French health ministry map showing spread of tiger mosquito since 2006 http://t.co/H8xYJmwXBn pic.twitter.com/vT2xqZRwAC— Ken Seaton (@apriliaken) June 10, 2015
You can calm your metabolic rate to some extent but pregnant or overweight people are liable to more attacks as they expel more CO2 and drinking wine or other alcohol increases your metabolic rate so will do the same.
Females are incredibly sensitive to CO2 and can sense if from 75ft – flying back and forwards through the vapour trail until it reaches the human on the other end.
Mosquitoes are also drawn to dark clothing because they generally fly close to the ground and see dark clothing easier than light clothing.
While mossies may seem to dodge your swiping newspaper with ease, they are actually rather slow fliers, at just 1.5mph, although their wings beat at up to 600 times a second.
As for chemicals to keep the mosquito at bay from adults, one of the most effective is DEET, although it has been linked to damage to the nervous system and can dissolve plastics.
Others such as IR3535 are said to be safe: despite it being known to cause eye irritation... plus also melting plastic and damage fabric.
Picaridin or icaridin-based products are odour-free and rated safe and as effective as DEET and IR3535 ... and are plastic-safe. Icaridin has not been tested for as long as DEET, however.
Oil of lemon eucalyptus – called huile d’eucalyptus citronné in France - is also rated as safe but has a very limited range. America’s Consumer Reports magazine rated it No1 for the first time, with DEET being dethroned.
The best answers are to stay indoors at dawn and dusk, when the wind dies down and mosquitoes can fly. As mossies cannot fly in winds stronger than 1mph, a good fan pointed in your direction would help. Otherwise, wear long trousers and tops with long sleeves.
If you do get bitten, you can try new electronic zappers that are just coming on to the French market that stop the itch quickly.
We take a look at environmentally-friendly ways to avoid bug menaces in next month's Connexion - you can ensure your copy by subscribing online here today for €35 for 12 issues.