The mozzie decides
There’s one in every crowd, the mozzie magnet, the person who claims that mosquitoes preferentially seek them out resulting in a disproportionate higher number of bites. Could there be any truth in this? According to researchers, mozzies choose their victims using a number of cues. Initially they are attracted to the carbon dioxide we breathe out. Body heat is important too. But once the mozzie gets closer, she (and it’s only the females that bite) responds to the smell of the victim’s skin. It’s believed blood type (particularly type O), pregnancy and beer drinking all make a person more attractive to mozzies (though results are known to vary for different species of mosquito). Lactic acid in sweat has also been shown to be a key mosquito attractant, but then there are up to 400 chemical compounds on the human skin that could also be playing a role in attracting the blood suckers. So, while it’s probably true that some people are more targeted than others, science is still a long way from providing any definitive answers as to why or what to do about it (other than a healthy application of insect repellent).
More info: see Cameron Webb’s discussion of mozzie biting preferences at the Conversation.