Why do mosquitoes bite me?

Have you ever noticed mosquitoes bite some people and not others? Or maybe you're the innocent victim of this evolutionary lottery? Why is it mosquitoes will be attracted to some and not others?

It's widely accepted that mosquitoes are attracted by CO2 emissions and therefore gravitate to people who emit more carbon dioxide. One theory says this is why mosquitoes are more attracted to pregnant women - the additional weight expectant mothers are carrying makes them breathe heavier, therefore emitting more carbon dioxide.

pregnant woman

But if you've ever been with a friend and you've been bitten but they haven't, then recent evidence suggests that some people give off masking odors that prevent mosquitoes from finding them.

In tests on body odor conducted way back in 2006, two different people put one hand into each end of a chamber full of mosquitoes and investigators noted which hand the mosquitoes preferred. They then selected the person who was not preferred and sealed their body in foil to collect their sweat. The body chemicals were analysed to identify if the secretions contained the anti-mosquito ingredients. The result? We'll have to be a little more patient as they are now waiting to patent the results in hopes of producing a natural insect repellent. But that suggests there are anti-mosquito properties in our sweat.

The answer may lie in an unexpected place - your socks. Experts working at the London School of Hygiene and Tropical Medicine have been conducting a rather smelly task. They've been collecting hundreds of dirty socks so they can test whether genetic factors dictate how "tasty" we are to mosquitoes.

Their experiment will see them analyse the specific odours of the socks and the genetic make-up of their owners, which include 100 twins from Gambia and the UK, to answer the age-old question about why some people get bitten more.

James Logan, a medical entomologist at the school, who is leading the work said: "We know very little about the genetics of what makes us attractive to mosquitoes.

"We hope this study will give us more insights into the mechanisms that help change our body doors to make us more or less attractive to mosquitoes. If we can identify important genes, perhaps we could develop a pill or medication that would allow the body to produce natural repellents to keep mosquitoes away."

We already know there are few things which makes us more appealing to a mosquito's palette.

1. If you emit more carbon dioxide than others.

2. People with type O blood tend to be more susceptible to bites.

3. As are people who drink more beer (sorry).

4. Pregnant women are more attractive to mosquitoes - especially those carrying malaria.

5. Having more bacteria on your skin can be a factor too.

spray mosquito repellent

Why do mosquitoes need to bite us at all?

It's a good question and is down to the female of the species (which is more deadlier than the male). The female mosquito is the one that bites (males feed on flower nectar). She requires blood to produce eggs. Her mouthparts are constructed so that they pierce the skin, literally sucking the blood out. Her saliva lubricates the opening and it’s the saliva plus the injury to the skin that creates the stinging and irritation we associate with mosquito bites. Ouch! 

Protect yourself! A gentle layer of mosquito repellent with DEET will give off enough odor to ward off mosquitoes. If you're going out at dawn or dusk (when mosquitoes are most active) wear loose fitting, coloured clothing to stop mosquitoes landing on your skin. 

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