Research suggests there may be some truth to mosquitoes preferring certain blood types, with evidence pointing to a slight preference for type O blood. A 2004 study published in the *Journal of Medical Entomology* found that Aedes aegypti mosquitoes landed on people with type O blood nearly twice as often as those with type A, while type B fell in between. This preference could be linked to chemical signals, like antigens secreted in sweat or skin, that vary by blood type and attract mosquitoes.
However, blood type is just one factor among many influencing mosquito attraction. Mosquitoes rely heavily on cues like carbon dioxide output, body heat, and compounds such as lactic acid or ammonia in sweat, which differ more between individuals than blood type alone. Genetics, diet, and even clothing color can also play bigger roles in who gets bitten, potentially overshadowing any blood type effect in real-world settings.
While the preference for type O is statistically notable in controlled studies, it’s not a definitive rule. Environmental factors and personal chemistry often outweigh blood type in determining bite frequency. So, while type O folks might face a slightly higher risk, no one’s immune—mosquitoes are opportunistic and will bite anyone available.