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Why Are Mosquitoes Attracted to Some People?


Why Are Mosquitoes Attracted to Some People?

There is no question that mosquitoes are more attracted to some people than others, and it seems, to some parts of the body over others. But who is really most susceptible and why?

The topic is, and has been, the subject of a great deal of government, university and private research for years. And it is a topic filled with fallacies and myths as well as fact. This isn't because anyone is purposely trying to spread falsehoods (excluding, of course, your little brother's comment on your smelly feet - which, in fact, truly are a mosquito attractant. Read on ...). Rather, it is primarily because there is so much that is unknown about it, and because each mosquito species can be attracted to different things.

According to the U.S. Department of Agriculture's Agricultural Research Service (USDA/ARS), "What may be attractive to one species may not be for another. For example, some species may be attracted to human blood while others may feed only on the blood of wild or domestic animals. Since there are 4-6 dozen mosquitoes out of 2,700 worldwide that transmit diseases, it can be tricky to pinpoint an attractant."

Additionally, according to the American Mosquito Association (AMA), more than 350 compounds have been isolated from odors produced by human skin, many of which attract mosquitoes - as well as other biting insects. Along with these compounds, some of the characteristics that have been scientifically proven to attract the attention of mosquitoes (if not your in laws) include the following.

Carbon Dioxide. Carbon dioxide is universally considered to be the greatest attractant to mosquitoes, and one which they can sense from more than 50 yards away. Because humans expel carbon dioxide with every breath, it is virtually impossible to keep mosquitoes completely at bay. As state by the AMA publication, "When female mosquitoes sense carbon dioxide they usually adopt a zigzagging flight path within the plume to locate its source."

However, there are variations in even this attractant, and other traits that will attract a mosquito to one person over another once it gets close to the group. Because larger people tend to exhale more carbon dioxide, this can cause them to be a more attractive target. If you ever noticed that a pregnant woman seemed to attract more mosquitoes, you were probably right - they, too, tend to exhale more carbon dioxide.

Fortunately for those heavier breathers, carbon dioxide is not the only trait that draws in mosquitoes. In fact, while their exhalations may bring the flying pests into the area, the mosquitoes are very likely to select another person in a group if they exude more of another competing attractant.

Movement, sweat, and heat. For example, mosquitoes are also attracted to visual stimuli as well as heat. So if members of a group are very active (playing volleyball, tennis, or other active sport), the combination of their increased exhalation, movement, sweat, and heated bodies are very likely to attract the mosquitoes over the person who is more sedentary.

Unless, that is, that sedentary person is drinking beer. A study published by the National Center for Biotechnology Information measured ethanol content in sweat, sweat production, and skin temperature before and after ingestion of 350 ml of beer (ethanol concentration 5.5%) by volunteers and compared them with a control subject. The results showed that the percent of mosquitoes landing on the volunteers significantly increased after beer ingestion compared with before ingestion.

Thus, all those who believe that having a single can of beer increases their attraction to the female sex are correct ... the females of the mosquito family that is.

Blood type. But no matter how much care you take, if you have the right blood, you may be a primary mosquito target. Another NCBI study found that people with Type O blood attracted more mosquitoes than any other blood type, and, for any blood type, people whose blood type can be distinguished by the mosquito were bitten more than those who did not secrete this odorant. Unfortunately both attributes are carried in one's genes, so there is little that can be done to combat this attractant.

Smelly feet. Another odor attractant over which a person does have a great deal more control is that of sweaty or unclean feet. USDA research, which equated the smell with that of Limburger cheese to which mosquitoes are highly attracted, showed that when CO2 was combined with smelly socks proved highly attractive to many common species of disesase-transmitting mosquitoes.

Besides helping to keep you from being bitten by mosquitoes, an understanding of the chemicals, compounds and characteristics that attract them can help researchers find new ways of controlling mosquitoes. As USDA/ARS noted, "If we can attract the mosquitoes to a trap, we can use this information to assess the mosquito distribution and population and develop ways to control them."

Article compiled from reports and studies by

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