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== Headline text STIMULI THAT ATTRACT MOSQUITOES

The factors involved in attracting mosquitoes to a host are complex and are not fully understood. Mosquitoes use visual, thermal, and olfactory stimuli to locate a host. Of these, olfactory cues are probably most important. For mosquitoes that feed during the daytime, movement of the host and the wearing of dark-colored clothing may initiate orientation toward a person. Visual stimuli seem to be important for in-flight orientation, particularly over long ranges, whereas olfactory stimuli become more important as a mosquito nears its host. It has been estimated that 300 to 400 compounds are released from the body as by-products of metabolism and that more than 100 volatile compounds can be detected in human breath. Of these odors, only a fraction have been isolated and fully characterized. Carbon dioxide and lactic acid are the two best-studied mosquito attractants. Carbon dioxide, released mainly from breath but also from skin, serves as a long-range airborne attractant and can be detected by mosquitoes at distances of up to 36 meters. Lactic acid, in combination with carbon dioxide, is also an attractant. Mosquitoes have chemoreceptors on their antennae that are stimulated by lactic acid. These same receptors may be inhibited by N,N-diethyl-3-methyl-benzamide (DEET)-based insect repellents. At close range, skin temperature and moisture serve as attractants. Different species of mosquitoes may show strong biting preferences for different parts of the human body (such as the head or feet), which may be related to local skin temperature and eccrine sweat gland output. Anhidrotic persons show markedly decreased attractiveness to mosquitoes. Other volatile compounds, derived from sebum, eccrine and apocrine sweat, or the cutaneous microflora bacterial action on these secretions, may also act as chemoattractants. Whole-host odors are more attractive than carbon dioxide and lactic acid alone. Floral fragrances from perfumes, soaps, lotions, and hair-care products may also attract mosquitoes. The attractiveness of different persons to the same or different species of mosquitoes varies substantially. In general, adults are more likely to be bitten than children, although adults may become less attractive to mosquitoes as they age. Men are bitten more readily than women. Larger persons tend to attract more mosquitoes, perhaps because of their greater relative heat or carbon dioxide output.