Some people really do get bitten more than others, and it’s not just bad luck. Roughly 20% of people are considered “high attractors,” drawing mosquitoes at noticeably higher rates than everyone around them. The reasons come down to a combination of your body chemistry, your genetics, what you’re doing at any given moment, and even what you’re wearing.
How Mosquitoes Find You
Mosquitoes locate you in stages, using different senses at different distances. From several meters away, they detect the carbon dioxide in your breath, your body odors, and your visual outline. As they get closer, they pick up on infrared heat radiating from your skin, but only after CO2 and human scent have already gotten their attention. In the final few inches, your body’s surface temperature becomes the dominant guide, helping them zero in on the best spot to bite. Blood vessels are the warmest points on your skin, and mosquitoes are remarkably good at finding them.
This layered detection system means there are multiple points at which your body can be broadcasting a stronger signal than the person standing next to you.
Your Skin Bacteria Matter More Than You Think
The microbes living on your skin produce the volatile compounds mosquitoes smell, and not all skin microbiomes are created equal. A study published in PLOS ONE found that people who were highly attractive to mosquitoes had significantly more bacteria on their skin but less diversity among bacterial species. In other words, having a few dominant types of bacteria made people more appealing than having a rich, varied mix.
Specific types mattered, too. People in the high-attraction group had 2.6 times more Staphylococcus bacteria on their skin compared to those mosquitoes avoided. Meanwhile, people mosquitoes found less appealing had about three times more Pseudomonas bacteria. The total bacterial count on the soles of participants’ feet directly correlated with how attractive they were to mosquitoes, which helps explain why ankles and feet are such popular bite zones.
Genetics Set Your Baseline
A twin study found that mosquito attractiveness has a heritability of about 62%. That’s a strong genetic component, comparable to the heritability of height. Identical twins were bitten at very similar rates, while fraternal twins showed much more variation between them. Your genes likely influence your attractiveness through the skin compounds you produce, your natural body odor profile, and the composition of your skin microbiome, all of which are at least partly inherited.
Blood Type Plays a Small Role
There is some evidence that mosquitoes prefer type O blood over other types, though the effect is modest. One study found a statistically significant preference for type O over type A, but the difference between type O and type B wasn’t significant. Blood type is far from the biggest factor, but if you’re type O and feel like a mosquito magnet, it may be contributing at the margins.
CO2 Output and Body Heat
Anything that increases your carbon dioxide output or raises your skin temperature makes you easier to find. Exercise checks both boxes: you breathe harder and your skin gets warmer. Larger body size also means more CO2 with every exhale.
Pregnancy is a particularly strong example. Pregnant women exhale about 21% more CO2 than non-pregnant women, and their body temperatures run higher. That combination makes them measurably more attractive to mosquitoes throughout pregnancy.
Drinking Beer Increases Your Appeal
A controlled study found that drinking a single beer significantly increased attractiveness to mosquitoes. After beer consumption, 47% of mosquitoes in a test chamber became activated, compared to 35-38% before drinking or after drinking water. Among mosquitoes that took flight, 65% oriented toward the beer drinker’s scent.
The surprising part: the researchers couldn’t pin down why. Beer didn’t increase the volunteers’ CO2 output, and it actually lowered their skin temperature slightly. Neither of those known attractors explained the effect. The leading theory is that alcohol metabolism changes the blend of volatile chemicals your skin releases, making your odor profile more appealing. So the effect seems to work through your scent rather than your breath or body heat.
What You Wear Can Help or Hurt
Mosquitoes do use visual cues, and color matters, though it depends on the species and time of day. Day-biting mosquitoes are attracted to a wide range of light wavelengths, meaning most colors can catch their attention. Night-biting mosquitoes, on the other hand, strongly avoid ultraviolet and blue light during daytime hours. Dark clothing tends to provide more visual contrast against most backgrounds, making you easier to spot. Light-colored, loose-fitting clothing is a simple way to reduce your visual signal.
Why Your Friend Never Gets Bitten
Given all these factors, the gap between people comes into focus. Your friend who never seems to get bitten likely has a more diverse skin microbiome, a naturally lower bacterial load on their skin, a body chemistry that produces fewer of the volatile compounds mosquitoes track, and possibly a non-O blood type. With 62% of attractiveness being heritable, they may have simply won a genetic lottery that shapes everything from their skin chemistry to their baseline odor.
You can’t change your genetics or your blood type, but you can reduce some signals. Showering after exercise lowers both your skin bacteria count and your surface temperature. Avoiding alcohol outdoors during peak mosquito hours removes one proven attractor. Wearing lighter-colored clothing reduces your visual profile. None of these will make you invisible, but stacking several small reductions can meaningfully cut down on bites.