In front of you are two plates. On one, a pile of lukewarm soggy cabbage, on the other, a large slice of freshly baked cake. Even if you’re not a picky eater, you’re bound to have preferences about what you greedily devour and what you politely decline. Mosquitoes are no different and have food preferences too. That’s right – some people are just tastier than others to the little flying pests.
What looks tasty to a mosquito?
Like us, a mosquito has a variety of senses it uses to choose a meal (or victim). First of all is its chemical sense (similar to what we call smell). But unlike us, mosquitoes aren’t interested in the aroma of freshly baked bread, but ‘sniff’ the air for the carbon dioxide – the gas that all of us breathe out.
Carbon dioxide is a fairly reliable sign that a tasty blood-pumping animal is somewhere close by, and mosquitoes can smell CO2 from a distance of up to 50m (163ft) using a part of their mouthpiece called the maxillary palp. And while the smell of sweat may not be particularly pleasant for humans, our perspiration contains several chemicals that are simply irresistible for mosquitoes (such as lactic and uric acid). This means that people who breathe more heavily, and those who sweat more, tend to be bitten more frequently than their lightly perspiring friends.
Most of us also exude chemical markers into the air that are specific to our blood type. Mosquitoes love to ‘smell’ all of these blood markers, but some blood types are particularly delicious. One study has shown that people with blood Type O get bitten almost twice as often as their Type A counterparts.
Smell is not the only sense a mosquito uses to pick out its next meal. We also think that they spot targets using their eyesight, and so it has been suggested that those who wear darker, more noticeable clothing may make themselves prone to bites.
What’s more, for mosquitoes, ‘hot’ really is synonymous for attractive – they sense body heat to home in on warm-blooded prey. No one is quite sure how this sense works, but a fairly recent discovery of similar temperature sensors in fruit flies is a promising start. Therefore, people with a higher skin temperature, such as skinny people, also often fall victim to mosquitoes.
Who is most likely to be bitten by a mosquito?
One group of people who have been found to be particularly vulnerable to mosquito munching are pregnant women. Soon-to-be mums have an unfortunate combination of higher respiration rate and higher body temperature, making them a perfect target for hungry mosquitoes.
Drinking alcohol could also be bad for attracting flies: one piece of research has shown that just a single beer can be a turn-on for peckish mosquitoes.
However, at the end of the day, the majority of factors determining your insect appeal (your level of chemical emission, body temperature, metabolism etc.) are controlled by genetics, meaning there’s not a huge amount you can do to stave off the 6-legged pests.
Of course you could just try to stop sweating. And breathing. Then again, dousing yourself in insect repellent doesn’t seem so inconvenient after all.
Answer by Nick Waszkowycz
Image: Jimmy Emerson on flickr