It is a common frustration to be the one person in a group singled out by mosquitoes while others remain untouched. This experience is not a matter of chance, as mosquitoes are sophisticated hunters guided by a highly developed sense of smell. They use this sense to detect specific chemical cues released by the human body, following a scent trail rather than biting at random.
The Main Chemical Attractants
Female mosquitoes, the sex that bites, use a combination of signals to locate a blood meal. The most significant long-range attractant is carbon dioxide (CO2), a gas that all vertebrates release with every breath. Mosquitoes can detect plumes of CO2 from as far as 150 feet away, using it as a general beacon that a potential host is in the vicinity. This gas alerts the mosquito that a potential host is nearby and initiates its host-seeking behavior.
As a mosquito gets closer, it begins to rely on short-range cues, where specific chemicals in human sweat become prominent. Lactic acid is a potent attractant secreted in our sweat, especially during and after physical exertion. The combination of elevated CO2 from heavier breathing and increased lactic acid on the skin creates a powerful lure. This pairing of signals helps the insect distinguish a human from other animals and guides its final approach.
Beyond lactic acid, other compounds found in sweat contribute to the scent profile that draws mosquitoes. Ammonia and uric acid are also present on the skin and are detected by mosquitoes. This complex blend of chemicals released through sweat provides the specific aroma that encourages a mosquito to land and bite.
Your Skin’s Unique Scent Signature
While certain chemicals are universally attractive to mosquitoes, the reason some individuals are “mosquito magnets” lies in their unique scent signature, which is a product of their skin microbiome. Human sweat is largely odorless on its own. The characteristic scent we identify as body odor is produced when communities of bacteria on our skin metabolize the compounds in sweat. This process creates a unique aromatic profile for every person.
The metabolic activity of skin bacteria releases a wide range of volatile organic compounds (VOCs), which are lightweight chemicals that travel through the air. It is this personal cloud of VOCs that mosquitoes analyze to determine how appealing a host is. The specific composition of a person’s skin microbiome directly influences the types and quantities of VOCs they produce, explaining the variation in attractiveness from one person to another.
Recent scientific investigations have pinpointed a specific class of VOCs that are especially alluring to mosquitoes: carboxylic acids. Research published in the journal Cell revealed that individuals who are highly attractive to mosquitoes consistently produce higher levels of these fatty acids on their skin. This trait was found to be stable over long periods. Conversely, people who are less attractive to mosquitoes appear to have a more diverse skin microbiome that produces a broader blend of scents, which may be less appealing.
Personal Factors That Increase Attraction
The specific chemical cocktail a person emits is influenced by several underlying factors. Genetics play a foundational role in establishing a person’s baseline scent profile. Studies involving twins show that identical twins have a much more similar level of attractiveness to mosquitoes compared to non-identical twins, suggesting a hereditary component. This genetic link likely determines aspects of both metabolic rate and the composition of one’s skin microbiome.
Diet is another factor that can temporarily modify a person’s scent. While many dietary claims lack strong scientific backing, the consumption of beer has been shown in studies to increase mosquito attraction. This is thought to be a result of changes in the chemical makeup of breath and sweat. The impact of other foods, such as bananas, is less conclusive, but some evidence suggests they may also increase attractiveness by altering lactic acid production.
Physiological conditions can also make an individual a more prominent target. Pregnant individuals, for example, are consistently found to be more attractive to mosquitoes. This is attributed to two main changes: they exhale approximately 20-21% more CO2 and have a slightly elevated body temperature.