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Just Curious

Why Do Bugs Love to Bug Me?

By Belinda Lanks
Conor McMeniman is an assistant professor in the Johns Hopkins Malaria Research Institute at the Bloomberg School of Public Health, where he studies how the mosquito nervous system detects and encodes human odor.

Some people consistently fall prey to mosquitoes and blood-sucking insects, while others seem to be protected from airborne onslaughts by an invisible force field. What gives? If you’re in the former camp, you’ve probably been swarmed by explanations for the attraction: It’s your blood type, or the food you eat.

Don’t believe everything you hear or read, Conor McMeniman says. “For the most part, those are just anecdotes. We don’t have studies large enough yet that can make those associations definitively.”

There are, however, a few known factors that enhance your attractiveness to flying bugs, including your personal scent signature, determined by a mix of genetics, diet, and physiology. McMeniman studies the combination of smells that attract blood-sucking insects and hopes his lab can develop strategies for luring them away from hosts. In the meantime, he has some tips for staying bite-free.

Human fragrance comprises hundreds of chemicals, but a couple of ingredients are irresistible to mosquitoes: lactic acid, which is a byproduct of respiration, and certain fatty acids released by skin bacteria. There is little you can do to control your lactic acid output, McMeniman says, but washing regularly to remove excessive body odor may help.

Mosquitoes are also drawn to the carbon dioxide we exhale. Insects from bedbugs to tsetse flies and mosquitoes use carbon dioxide as a way to locate living vertebrates, McMeniman says. Drinking alcohol can boost those telltale CO2 emissions.

Carbon dioxide and body odor can carry downwind and attract mosquitoes. As the insects get closer, they see their potential human target, especially if it forms a strong visual contrast with its environment. Clothing that blends into the surroundings—a sand-colored bathing suit on the beach, for instance—can potentially throw off an attacker. Covering your body helps, but McMeniman cautions against spandex, which is pervious to a mosquito’s proboscis, the tiny spear it uses to suck blood.

For the bite-prone and anyone living in areas of mosquito-carried disease, McMeniman recommends three precautions. First, minimize time outdoors when mosquitoes bite. Peak biting for the West Nile virus–spreading Culex species is from dusk to a few hours after dark—prime summer barbecuing hours.

Second, McMeniman encourages taking measures to protect your home by using screens on windows and removing standing water that can act as a breeding site. Drain the source or consider applying an insecticide that kills mosquitoes in their larval stage. For permanent pools of standing water such as rainwater tanks, make sure they’re covered.

And third, when outdoors, he suggests wearing an EPA-registered insect repellent, such as DEET, picaridin, or IR3535. Those looking for a natural deterrent can try oil of lemon eucalyptus.

Illustration of two mosquitoes having a picnic under the night sky
Joren Cull

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