Why Do Mosquitos Bite Some People More Than Others? Your Blood Type, Sweat Contents and Even Alcohol Consumption May Make You More Attractive to the Pesky Insects
Scientists are working hard to discover the factors that drive the blood-sucking insects to target certain individuals
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You come in from a summer hike covered with itchy red mosquito bites, only to have your friends innocently proclaim that they don’t have any. Or you wake up from a night of camping to find your ankles and wrists aflame with bites, while your tentmates are unscathed.
You’re not alone. An estimated 20 percent of people, it turns out, are especially delicious for mosquitoes and get bit more often on a consistent basis.
Scientists are working hard to find out why the insects prefer some people more than others, because in many places the bites are more than just an inconvenience. Malaria is transmitted when a mosquito carrying the malaria parasite bites a victim. Roughly 250 million estimated cases of the disease occurred in 2022, leading to more than 600,000 deaths. Mosquitos also spread other deadly diseases, including dengue fever and yellow fever. And as the climate changes, the ranges for mosquitos and the diseases they carry, which also include Zika and West Nile, are shifting.
As scientists work on ways to prevent bites—beyond bed nets and insect repellents (which, we’ve discovered, some mosquitoes can become immune to over time)—they continue to look into why some of us are bitten more than others. Here are some of the factors that could play a role.
Blood type
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Not surprisingly—since, after all, mosquitoes bite us to harvest proteins from our blood—research shows that they may find certain blood types more appetizing than others. One 2004 study found that in a controlled setting, mosquitoes landed on people with Type O blood nearly twice as often as those with Type A. People with Type B blood fell somewhere in the middle of this itchy spectrum. In a 2019 study, mosquitos were given the opportunity to go to feeders with all four blood types, and they picked the Type O feeder most often. Additionally, in the 2004 study about 85 percent of people secreted a chemical signal through their skin that indicated which blood type they have, while 15 percent did not, and mosquitoes were more attracted to secretors than non-secretors regardless of which type they were.
Carbon dioxide
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One of the key ways mosquitoes locate their targets is by sensing the carbon dioxide emitted in their breath—they use an organ called a maxillary palp to do this. Mosquitos can detect carbon dioxide from as far as 100 feet away. And at long or medium distances from the bugs, people who simply exhale more of the gas over time have been shown to attract more mosquitoes than others.
Exercise
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Mosquitoes find victims at closer range by smelling a chemical cocktail of odors that can include lactic acid, ammonia and other substances expelled via human sweat, and they are also attracted to people with higher body temperatures (more on that next). Because strenuous exercise increases the buildup of lactic acid and heat in your body, it likely makes you stand out to the insects.
Warmth
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Heat can draw mosquitos in, with an individual’s body temperature playing a role in guiding the insects, but the mechanisms mosquitos use to sense warmth can be turned off. When researchers were able to disable a molecular thermostat in mosquito antennae, the scientists reduced the insect’s ability to detect heat, leaving it less likely to feed on warm human blood. That 2020 find, published in Science, may help researchers develop repellants. But disabling the sensor isn’t enough to completely stop mosquitos, which can rely on other cues to find their target.
Skin bacteria
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Other research has suggested that the particular types and volume of bacteria that naturally live on human skin affect our attractiveness to mosquitoes. In a 2011 study, scientists found that having large amounts of a few types of bacteria made skin more appealing to mosquitoes. Surprisingly, though, having lots of bacteria but spread among a greater diversity of different species of bacteria seemed to make skin less attractive. This might be why some mosquitoes are especially prone to biting our ankles and feet—where many stink-producing bacteria thrive. Some scientists think one way to deter mosquitos from biting humans may be to alter bacterial communications that attract the insects.
Taste
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In 2024, Yale University researchers discovered that different tastes may influence biting, feeding and even egg-laying in mosquitos. Certain compounds in human sweat led mosquitos to bite more, while other bitter compounds suppressed feeding behavior. Not only that, combinations of compounds affected behavior. While some amino acids and salt did not alter biting when presented to the insects on their own, when they were combined, more biting ensued—a result that makes sense since both compounds are found together on human skin. But as in so many other cases, not all humans were equal. When presented with different sweat samples, mosquitos bit some options more often. “We think this could be part of the reason why some of us get bitten by mosquitoes a lot more than others,” says biologist John Carlson, the paper’s senior author. “Some people may just taste better to mosquitoes.”
Beer
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Just a liter of beer can make you more attractive to the insects, one 2010 study found. Researchers tested whether beer may have altered carbon dioxide or body temperature and attracted the insects, but they found neither of these factors were correlated with increased attention, making mosquito affinity for drinkers something of a mystery.
Pregnancy
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In multiple studies, pregnant women have been found to attract roughly twice as many mosquito bites—from certain species that carry malaria—as other women. At least two key factors may be at play. Pregnant women exhale about 21 percent more carbon dioxide and are on average about 1.26 degrees Fahrenheit warmer around the belly than other women.
Clothing color
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This one might seem absurd, but a common mosquito species uses vision (along with scent) to locate humans, so wearing colors that stand out (black, red, orange, cyan) may make you easier to find, according to a 2022 study led by scientists at the University of Washington. Most of the preferred hues correspond to longer wavelengths of light, which human skin also gives off. Colors including green, purple, blue and white were ignored by the species in the research.
Genetics
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As a whole, underlying genetic factors are a key driver in the variability among people in their attractiveness to mosquitoes—regardless of whether it’s expressed through blood type, metabolism or other factors. In 2015, researchers even found that some body odors mosquitos sense may have a genetic basis. As advancements in genetic research related to mosquitoes continues, researchers are looking to innovative ways to deter the insects, like …
Natural repellants
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For years researchers have looked at the reasons why a minority of people seem to rarely attract mosquitoes in the hopes of creating the next generation of insect repellants. Scientists dream of creating drugs that could increase the production of natural repellents in the skin or making a bacteria-based product that could deter mosquitos for weeks. Eventually, future inventions might even make it possible for a Type O, exercising, pregnant woman in a red shirt to ward off mosquitoes for good.
