It often seems that some individuals are relentlessly targeted by mosquitoes while others escape relatively unscathed. This common experience leads many to question what makes one person more appealing to these biting insects. While popular belief often points to blood type, scientific research reveals a more complex interplay of factors.
Primary Attraction Factors
Mosquitoes are highly adept at locating their targets, primarily relying on cues like carbon dioxide, body heat, and specific body odors. Carbon dioxide (CO2) is a major attractant, detectable by mosquitoes from significant distances, sometimes up to 164 feet away. Individuals who exhale more CO2, such as during exercise or pregnancy, tend to be more attractive.
Body heat serves as another important signal for mosquitoes. They can detect and home in on warmer bodies or areas of the body with higher temperatures. People with elevated body temperatures, whether from physical activity or naturally running warmer, may attract more mosquitoes.
Body odor plays a substantial role, as mosquitoes are drawn to compounds present on human skin. Sweat contains lactic acid and ammonia, which are appealing scents. The unique mix of bacteria on each person’s skin interacts with sweat to produce distinct odors, and certain bacterial compositions can make individuals more attractive. Physical exertion increases both CO2 exhalation and body heat, further enhancing attractiveness.
Blood Type and Secretor Status
Research indicates mosquitoes may show a preference for Type O blood. Studies have found that mosquitoes landed on people with Type O blood nearly twice as often as those with Type A blood. While Type B blood falls in the middle, Type A is considered the least attractive to mosquitoes.
Beyond blood type, “secretor status” also influences mosquito attraction. Approximately 80% of people are “secretors,” meaning they secrete chemical markers of their blood type through their skin. Studies suggest that secretors are more likely to attract mosquitoes, regardless of their specific blood type, because these chemical signals are detectable on the skin. For instance, Type O secretors are more attractive to mosquitoes than Type A secretors.
The Purpose of the Bite
Female mosquitoes bite humans and other animals out of a biological necessity for reproduction. They require a “blood meal” to obtain the proteins and nutrients needed to develop their eggs. Without this blood, the female mosquito cannot produce viable eggs.
Male mosquitoes, in contrast, do not bite humans or animals. Their diet consists solely of plant nectar and other sugary fluids, which provide them with energy. The female’s need for a blood meal drives her host-seeking behavior, making her responsible for the itchy bites and the transmission of potential diseases.