Science

Why Do Mosquitoes Bite Some People More Than Others?

A mosquito bites a person
Manjunath Kiran/Getty Images

Summer is prime time for mosquitoes. Yet, despite spending most summers in the Northwoods of Wisconsin, I manage to come home unscathed. But not everyone is as lucky—mosquitoes have preferences. Why do mosquitoes bite some people more than others?

One reason has to do with mosquitoes’ main target: blood. Contrary to popular belief, mosquitoes do not feed on animal blood for food. In fact, only female mosquitoes do the biting, as the blood meal is necessary for reproduction. And scientists have found they prefer one type over the rest. A 2004 study demonstrated that mosquitoes were more attracted to Type O. This was also supported by a 2019 study, where mosquitoes, when presented with different types of blood, had a higher blood-feeding preference for Type O.

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Bacteria on the skin itself can play a role in how attractive you may be. Mosquitoes are also attracted to certain bodily emissions. The irritating insects have organs called maxillary palps that allow them to detect carbon dioxide from their prey. So if you’re someone who releases a lot of, well, gas, you may be more of a target. (This is also why pregnant women are mosquito magnets: They reportedly exhale about 21 percent more carbon dioxide). Molecules that humans expel through sweat, such as ammonia and lactic acid, also seem to attract the little guys. The mentioned attractants could be due to individual differences that can be explained by genetics. Researchers observed a genetic basis for attractiveness to mosquitos in a 2015 study that looked at twins.

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There are some incidental factors that could play a role in whether mosquitoes are drawn to you. Although the critters do rely on scent, they also use their simple visual system to locate potential targets. Thus, vibrant colors that draw attention would be more likely to lure them in.

Another seemingly random attractant? Beer. As mosquito scientist Grayson Brown told CBS News in 2016, it’s not clear why, but it could be because “alcohol raises the body temperature of drinkers and makes them sweat more” and “C02 that fizzles out of a beer bottle when its top is popped could be an attraction factor, too.” Who knew sobriety could be a natural mosquito repellent?

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