Only female mosquitoes bite, as they require blood to produce eggs. Male mosquitoes feed on nectar for energy. This need for a blood meal drives females to actively seek hosts. Understanding what draws these insects to certain individuals reveals the science behind mosquito attraction.
The Blood Type Connection
Human blood types (A, B, AB, O) are distinguished by specific antigens on red blood cells. Research indicates mosquitoes prefer certain blood types, with studies suggesting individuals with Type O blood are more attractive, showing a higher landing preference compared to Type A.
Approximately 80% of people are “secretors,” meaning they secrete blood type antigens into bodily fluids like sweat. Mosquitoes are drawn to these secretions, making secretors generally more appealing regardless of their specific blood type. The H antigen, a precursor to A and B antigens, is secreted by Type O individuals. This may contribute to the observed preference for Type O secretors. While blood type plays a role, it is one of several factors influencing mosquito attraction.
Key Attractants Beyond Blood Type
Mosquitoes use a combination of cues to locate their hosts, often more influential than blood type alone. Carbon dioxide (CO2) is a primary long-range attractant, detectable by mosquitoes from distances up to 150 feet. Individuals who exhale more CO2, such as during exercise or pregnancy, tend to be more attractive. The concentration of CO2 is highest near the mouth and nose, which explains why mosquitoes often buzz around the head.
Body heat is another significant attractant. Female mosquitoes detect warmth and are drawn to warmer bodies. Factors that increase body temperature, like physical activity or hot weather, can make a person more appealing.
Sweat contains various chemicals that are potent mosquito attractants. Lactic acid, ammonia, and uric acid are key components in sweat that draw mosquitoes. Lactic acid levels increase with physical activity, increasing attraction. The unique composition of an individual’s skin microbiome also produces distinct volatile compounds when interacting with sweat. These unique odor profiles can make some people more attractive to mosquitoes than others.
Genetics play a role in determining an individual’s unique body chemistry, including the composition of sweat, body odor, and skin microbiome. These inherited traits influence a person’s appeal to mosquitoes. Additionally, clothing color affects visibility; dark colors like black, red, orange, and cyan absorb more heat and create a stronger contrast against the background, making wearers more noticeable and attractive. Lighter colors, such as white, green, or blue, are less attractive.
The Science Behind Mosquito Detection
Mosquitoes use various sensory organs to detect hosts. Their antennae and maxillary palps sense chemical cues from the environment. These organs are highly attuned to carbon dioxide, allowing mosquitoes to detect exhaled breath from a distance and initiate host-seeking behavior. They also detect other volatile chemical signals released from skin and sweat.
Specialized thermal sensors detect body heat, guiding mosquitoes towards warmer areas. This helps them identify warm-blooded hosts and locate blood vessels.
Highly sensitive olfactory receptors detect specific chemicals in sweat, skin odors, and breath. These receptors discern the complex chemical cocktail of human body odor, including lactic acid and ammonia. The combination of CO2 with these odorants enhances attraction. Visual cues also play a part at closer ranges, as mosquitoes use sight to identify hosts based on movement, contrast, and color. They are drawn to dark colors due to heat absorption and contrast.