So THAT'S Why Mosquitoes Bite Some People More Than Others

If you’ve ever been at an outdoor party or BBQ during the fading hours of daylight and don’t personally notice an increase in the number of mosquitoes, you’ll probably hear someone complaining about it. That’s because mosquitoes are selective insects, and some people are more likely to get bites than others.

There are a few factors that could contribute to why this happens: In one controlled study by the Journal of Medical Entomology, the bugs landed on people with blood Type O nearly twice as frequently as those with Type A. The researchers noted this has to do with secretions we produce, which tips mosquitoes off on a person’s blood type.

More research needs to be conducted on mosquitoes’ potential preference for certain blood types over others, said Jonathan F. Day, an entomology professor at the University of Florida. But he agreed that mosquitoes do pick up on some cues we give off that make the bugs more likely to land on certain people.

“These cues let them know they are going to a blood source,” Day said. “Perhaps CO2 is the most important. The amount of CO2 you produce, like people with high metabolic rates ― genetic, other factors ― increases the amount of carbon dioxide you give off. The more you give off, the more attractive you are to these arthropods.”

But what separates us from the nonliving entities that give off carbon dioxide, like cars? Mosquitoes look for primary cues in conjunction with what Day calls “secondary cues.”

Lactic acid — the stuff that causes our muscles to cramp during exercise — is one of those secondary cues, for example. Lactic acid is released through the skin, signaling to mosquitoes that we are a target, Day said.

Mosquitoes also have other qualities that help them pick up on