It’s All That Exhaling That Draws Mosquitoes

What’s worse than getting eaten alive by mosquitoes at the family barbecue? Noticing that your brother-in-law, sitting right next to you, is mosquito-free.

The minuscule buzz-bombers are quite discriminating when it comes to human targets, according to Theodore Andreadis, chief medical entomologist at the Connecticut Agricultural Experiment Station in New Haven. He notes, however, that the blood-snacking preferences of mosquitoes are not well understood.

A major attractant, according to Andreadis, is carbon dioxide, , which we’re constantly exhaling in various amounts. That fact may account for research that suggests that mosquitoes seem to be more attracted to adults than children, because an adult is physically larger than a kid and therefore is puffing lots more carbon dioxide into the atmosphere. (But there is conflicting research on adults versus children, Andreadis notes.)

The carbon dioxide factor might also explain why mosquitoes are more drawn to people when they’re near domestic animals. Or this may have something to do with the appeal of body odors. The bloodthirsty bugs apparently are drawn to foot odor as well as a light layer of sweat and higher body temperature--but not dripping sweat. Lactic acid, secreted by the skin in varying amounts by different people, is another lure. Dark skin and dark clothing are more appealing to the critters than lighter skin and clothing.

One new study from Japan may put a slight damper on certain kinds of outdoor merrymaking.

It suggests that people who drink alcohol attract more mosquitoes than those who stay with soft drinks.

It’s all a bit up in the air, Andreadis said.

There are clear variations among mosquito species. If you are a chosen target, don’t take those bites personally. Female mosquitoes suck blood so that they can produce eggs. “They’re just doing it to sustain themselves,” Andreadis said.