Mosquitoes are a common warm-weather nuisance, with some individuals frequently receiving more bites than others. This disparity is not random; mosquitoes are highly attuned to specific signals that help them locate their next blood meal. Female mosquitoes, which require blood for egg production, use a sophisticated array of senses to pinpoint hosts. They rely on a combination of chemical cues, physical signals, and individual characteristics.
Chemical Attractants
Mosquitoes primarily detect humans through the chemical compounds they emit. Carbon dioxide (CO2) is a primary long-range attractant, signaling a potential host. Mosquitoes can sense CO2 plumes from distances up to 150 feet away, using specialized receptors to detect changes in CO2 concentration and guide them towards the source. The more CO2 a person exhales, such as during exercise, the more attractive they become.
As mosquitoes draw closer, other chemical signals become important. Lactic acid, produced in human sweat during physical activity, is a significant close-range attractant. Ammonia and various fatty acids, also present in sweat and skin odor, contribute to this chemical signature. The unique blend of these compounds, influenced by skin microbiota, creates a distinct personal scent that mosquitoes find appealing.
Physical Cues
Once within closer range, mosquitoes use physical cues to hone in on a host. Body heat is a significant factor, as female mosquitoes are highly sensitive to warmth, indicating a warm-blooded individual. They use heat-sensing organs to detect infrared radiation emitted, allowing them to pinpoint warm areas like the head, neck, and extremities.
Movement also plays a role in attracting mosquito attention. Motion can signify a living target, making moving individuals more noticeable. Visual cues, particularly certain colors, also draw mosquitoes in. Once they detect CO2, mosquitoes are drawn to colors such as red, orange, black, and cyan. Darker clothing, including black, navy, and red, stands out and absorbs more heat, making a person more attractive.
Personal Characteristics
Beyond universal attractants, individual physiological differences influence a person’s susceptibility to mosquito bites. Research suggests blood type plays a role, with some studies indicating Type O blood might be more attractive to mosquitoes. While the exact mechanisms are still under investigation, Type A blood appears less attractive.
Pregnancy is another factor increasing mosquito attraction. Pregnant individuals typically exhale more carbon dioxide and have a higher average body temperature, both strong attractants for mosquitoes. Studies have found that pregnant women can attract up to twice as many mosquitoes as non-pregnant individuals. Alcohol consumption has also been linked to increased mosquito attraction, possibly due to changes in body odor or elevated skin temperature after drinking.