The rainy season means pools of stagnant water are lying everywhere and the mosquitoes are busy than ever before spreading what they know best.  Globally, these killer mosquitoes spread malaria, yellow fever, dengue fever and other deadly diseases – the ebola disease being one of them.  And when it comes to a good bloody meal, mosquitoes are much fussier than you might think. 

Women tend to suffer more than men because they tend to bare more flesh.  But it’s often said that some people attract mosquito bites, regardless of their sex, while others never get nipped and increasing studies are showing that mosquitoes really do prefer some people to others.  So what determines if you’re one of the miserable people loved by the blighters – or one of the lucky few they ignore?

Carbon dioxide

Female mosquitoes use a range of techniques to find prey.  But one of the most important is the presence of carbon dioxide – the invisible, odourless gas we breathe out.  They use an organ called the maxillary palp to spot clouds of carbon dioxide before homing in on the source. 

This organ is so finely tuned that it can detect the gas from more than 160ft away.  Larger people tend to have higher metabolic rates – they burn up more energy when their bodies are resting.  This is because their bodies are bigger and more energy is needed to pump blood and keep moving. 

And because they are burning up more fuel all the time, they produce more carbon dioxide – a by-product of converting food into energy – than people with lower metabolic rates.  This makes them more noticeable to mosquitoes.

There is some evidence that people who are tall or fat are also at greater risk simply because they are bigger, according to a study by world mosquito expert Dr. James Logan, published in the journal BioMed Central in 2010.  Going for a big host is not a bad strategy for the mosquitoes as larger people have more surface area and more skin that’s likely to be exposed.

Body odour and sweat

Mosquitoes appear to adore the smell of a hot, sweaty human.  The reason they find some people more attractive than others is usually down to smell, says Dr. Logan.  ‘They hear and detect moisture and temperatures, but the sense of smell is most important and we all smell slightly different,’ Human bodies produce around 500 different volatile chemicals that waft off our skins into the air.  Many of these can be detected by mosquitoes using a pair of tiny feathery antennae  on their heads.  Studies have shown the insects are attracted to sweat, lactic acid, uric acid and octenol.

Lactic acid is released through pores in the skin, particularly after exercise.  Uric acid is best known as a chemical in urine, but can also build up in the skin.  Octenol is found in sweat and breath – so if you’re sweaty or breathing heavily, you’ll produce more, attracting mosquitoes. 

Some people naturally release more of these chemicals than others.  If you exercise outside you tend to produce more lactic acid.  Mosquitoes also seem to like higher body temperatures, and body temperature goes up when we exercise – another reason why you may be more prone to bites after a work-out.


Life isn’t fair for pregnant women.  Not only do you get hot and tired, you are also more vulnerable to mosquito bites.  Studies show that pregnant women are more attractive to mosquitoes, getting twice as many bites as non-pregnant women for several possible reasons.  Pregnancy raises the body temperature by about 1.3f, and mosquitoes are attracted to warmer people. 

It can also make women sweat more.  Pregnant women tend to breathe out more carbon dioxide, which attracts the insects.  A women’s skin odour may change subtly during pregnancy too, influenced by hormonal changes in her body, and this change could make them smell sweeter to mosquitoes.

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