Mosquitoes bite you because of a combination of signals your body constantly broadcasts: the carbon dioxide you exhale, the specific blend of chemicals on your skin, your body heat, and even the colors you wear. Some people genuinely do get bitten more than others, and the reasons are largely biological, stable over time, and in many cases inherited.
How Mosquitoes Find You
A mosquito locates you in stages. From as far as 30 to 160 feet away, it picks up the plume of carbon dioxide you exhale with every breath. CO2 acts as a general dinner bell for all blood-feeding mosquitoes, signaling that a warm-blooded animal is nearby. Every vertebrate exhales it, so at this stage the mosquito isn’t choosing you specifically. It’s just heading in your direction.
As it gets closer, other cues take over. Your skin releases hundreds of volatile compounds, and the mosquito’s antennae are lined with receptors tuned to detect specific ones. Lactic acid, a natural byproduct of metabolism that concentrates on your skin and in sweat, is one of the strongest attractants. Ammonia and a compound called 2-ketoglutaric acid also play significant roles. These chemicals mix with CO2 to create a scent profile that mosquitoes find far more compelling than CO2 alone.
Within a few feet, body heat and visual cues come into play. Mosquitoes are drawn to dark colors, particularly red, orange, and black. Research from the Journal of Experimental Biology found that in the presence of CO2, mosquitoes strongly preferred wavelengths above 600 nanometers (the orange-to-red range) and showed attraction to black surfaces, while largely ignoring greens and blues. Your body heat also creates convection currents that carry your scent chemicals upward and outward, essentially making you easier to “see” from a sensory perspective.
Why Some People Get Bitten More
If you feel like mosquitoes single you out while leaving others alone, you’re probably right. A study published in PLOS ONE estimated that about 62% of the variation in how attractive people are to mosquitoes is heritable. That’s a remarkably high number, meaning the tendency to attract mosquitoes runs in families much the way height or eye color does.
The mechanism behind this appears to be your skin’s chemical signature. Research supported by the National Institutes of Health found that people who attracted the most mosquitoes had significantly higher levels of carboxylic acids on their skin. Carboxylic acids are fatty acid compounds produced partly by your skin’s oil glands and partly by the bacteria living on your skin. Critically, these levels stayed stable for a year or more regardless of changes in diet, environment, or hygiene. Among the most attractive people, the specific blends of carboxylic acids differed from person to person, suggesting there’s no single “mosquito magnet” chemical but rather a range of appealing profiles.
This is why two people sitting side by side outdoors can have completely different experiences. Your skin microbiome, the unique colony of bacteria on your skin, processes your natural oils into volatile compounds that either attract or fail to attract mosquitoes. You can’t scrub this away or meaningfully change it with soap.
What About Blood Type?
The idea that mosquitoes prefer type O blood is one of the most persistent claims about mosquito bites. According to the Chinese Center for Disease Control and Prevention, there is currently no evidence that blood type makes a difference in attractiveness to mosquitoes. The chemicals mosquitoes detect are on the surface of your skin and in the air around you. They can’t sense your blood type before biting.
Exercise, Drinking, and Temporary Changes
While your baseline attractiveness to mosquitoes is largely fixed by genetics and skin chemistry, certain activities can make you temporarily more appealing. Exercise increases your CO2 output, raises your body temperature, and floods your skin with lactic acid and ammonia through sweat. All three of these are primary mosquito attractants, which is why you tend to get swarmed during or just after a workout.
Drinking alcohol also increases your attractiveness. A controlled study found that after drinking beer, volunteers attracted 47% of mosquitoes compared to 35% before drinking. Mosquitoes were also 77% more likely to fly toward a person’s scent after that person consumed beer. The researchers couldn’t pinpoint exactly why, since alcohol didn’t consistently raise CO2 output or skin temperature across all subjects. Something about the metabolic changes from alcohol shifts your scent profile in a way mosquitoes find appealing.
Pregnancy is another well-documented risk factor. Pregnant women exhale more CO2 and have elevated body temperatures, both of which increase their visibility to mosquitoes.
Things That Don’t Work
Eating garlic and taking vitamin B supplements are two of the most common home remedies people try. Neither works. Controlled trials at the University of Wisconsin tested both approaches using placebo-controlled designs where volunteers took either the remedy or a sugar pill, then had their attractiveness to mosquitoes measured in a lab. Garlic showed no effect. Vitamin B showed no effect. Your diet has minimal influence on the skin compounds mosquitoes are actually detecting.
Not All Mosquitoes Want You Equally
There are over 3,500 species of mosquitoes, and they don’t all behave the same way. Some species are human specialists, genetically wired to seek out people even when other animals are abundant. The yellow fever mosquito (Aedes aegypti) and the primary African malaria mosquito (Anopheles gambiae) both fall into this category. They have olfactory receptors specifically tuned to human skin chemicals like lactic acid, and they maintain their preference for humans regardless of what other hosts are available.
Other species are opportunists. Many Culex mosquitoes, the kind common in backyards across North America, prefer birds but will readily switch to biting humans when bird populations decline seasonally due to migration. This is one reason mosquito bites can feel worse at certain times of year: it’s not just that mosquito numbers are up, but that the local species may be shifting their attention to you as their preferred hosts disappear.
What You Can Actually Control
You can’t change your genetics, your skin microbiome, or your CO2 output in any meaningful way. But the factors you can control do make a difference. Wearing light-colored clothing in whites, light blues, and greens reduces visual attraction. Avoiding outdoor exercise during peak mosquito hours (dawn and dusk for most species) limits the combination of heat, sweat, and CO2 that makes you especially detectable. Using fans on a porch or patio disrupts the CO2 plume that leads mosquitoes to you in the first place, since they’re weak fliers that rely on following scent trails through still air.
EPA-registered repellents containing DEET, picaridin, or oil of lemon eucalyptus work by masking or interfering with the skin chemicals mosquitoes use to locate you. They don’t kill mosquitoes or make you invisible. They disrupt the chemical conversation between your skin and the mosquito’s sensory system, which is ultimately what this entire process comes down to: a chemical signal you never chose to send.