You really are a mosquito magnet. Here’s what you can do about it.
New research proves these bloodsuckers can pick you out in a crowd. Here are the odors they’re drawn to, what scientists recommend to keep them away—and how a future personalized repellant might work.
Mosquitoes love Kim Zarins. The insects’ preference for Zarins, an English professor at Sacramento State University, is so extreme that her 20-year-old son likes her to come outside with him because she serves as a decoy and “he knows he’ll be safe,” Zarins says.
But now, mosquito magnets like Zarins are helping scientists pinpoint what entices these thirsty bloodsuckers, and there’s new hope for relief.
(Are we entering a new era of mosquito control?)
More than just a nuisance, mosquitoes can carry devastating illnesses like Zika, dengue fever, malaria, and West Nile disease, and are responsible for over a million deaths every year. And while historically, they have been more prevalent in tropical climates, mosquitoes carrying disease-causing organisms have expanded their reach as the planet warms—including in parts of the United States like Connecticut, California, and Arizona.
Mosquitoes use a variety of cues to home in on their targets. Odor distinguishes people from other animals, and some mosquitoes have evolved to seek out our unique bouquet. From up to 200 feet away, they follow the carbon dioxide plumes we exhale with each breath. As they approach several feet closer, they smell the odors emanating from our feet, underarms, and skin. At around 50 feet, they begin to see us as dark silhouettes against the light. Finally, pools of heat guide them to the choicest sites on which to land while taste receptors on their feet help them decide where to bite.
(First-Ever Evidence That Mosquitoes Can Be Trained)
What mosquitos like to smell
“It’s very striking how good mosquitoes are at detecting us,” says Diego Giraldo, a neuroscientist at Johns Hopkins and co-author of a 2023 John Hopkins study that characterizes human odor profiles that attract Anopheles gambiae, an African mosquito that transmits malaria. The research shows, for the first time, that mosquitoes can discriminate between multiple people in a large, spacious arena the size of an ice-skating rink. Previous studies used much smaller chambers and pitted one person against another.
(To fight malaria, scientists want to poison mosquitoes—with human blood.)
The arena used in Giraldo’s experiment was connected to eight tents via air ducts, which funneled odors from each tent’s occupant over a black, heated disk located in the experimental space. Infrared cameras captured the movements of mosquitoes that landed on each disk.
Over the course of the experiment, mosquitoes were four times more likely to land on the disk associated with the subject who attracted the most mosquitoes compared to the subject who attracted the least. “This just drives home the point that even in complex situations with multiple sources of odor, mosquitoes do seem to prefer some people over others,” Giraldo says.
Next, the researchers identified the chemicals in each subject’s odor profile using an instrument that can separate the gases making up the sample into its component parts. “Human odor, however, is incredibly complex,” says Stephanie Rankin-Turner, a chemist, now at the University of Pittsburgh, who also worked on the study. In human odors, “there are a lot of chemical compounds that no one’s ever classified before.” To narrow the field, the researchers focused on chemicals known to make up human scent.
Their analysis uncovered 15 airborne compounds that were present in the odors produced by all subjects. But it was the concentrations of these various chemicals that determined how likely mosquitoes were to bite them. “If there’s a compound that mosquitoes really love and one person is releasing a lot of it, then that has the potential to increase their attractiveness to mosquitoes,” says Rankin-Turner.
The mosquitoes were especially beguiled by carboxylic acids, a class of fatty acids found in human sweat with a scent that is sometimes compared to rancid butter or cheese, confirming earlier work demonstrating a similar preference in another mosquito species. We produce these acids in our sebum, the oily layer that protects our skin, but they’re also made when beneficial microbes living on our skin surface digest our secretions.
The insects were also drawn to acetoin, which is produced by skin microbes too. “It definitely seems like the skin microbiome is playing a big role in how we smell and how attractive we are” to mosquitoes, Rankin-Turner says.
And while factors like pregnancy, disease status, or what we eat and drink can influence our scent, some of its features are remarkably stable, persisting across months and even years. This aligns with the observation that certain people, like Zarins, the English professor, tend to attract mosquitoes.
“A lot of us in the field want to understand what makes one person more attractive than another person because that secret may allow us to make the next generation repellent,” says Matthew DeGennaro, a mosquito geneticist at Florida International University, who was not a part of the study. He cited the naturalistic, almost field-like conditions the researchers were able to achieve as a significant step towards further teasing out these associations.
Fooling mosquitoes
Most people use personal care products like shampoo and deodorant every day, so if body odor can attract mosquitoes, perhaps washing or layering scents on top of it can confuse them. But the reality is more complex, as scientists discovered in a proof-of-concept study that explored how these soaps impact mosquitoes’ ability to track us.
For their initial experiment, the researchers compared the number of times mosquitoes landed on a nylon sleeve that had been worn on the unwashed arm of a subject versus one that had been worn on the same subject’s washed arm. The experiment was repeated across four different subjects using four different soaps, including brands like Dial and Native.
To the researchers’ surprise, in some cases, washing increased the number of mosquito landings, indicating that soap amplified that person’s attractiveness to mosquitoes. But the effect wasn’t consistent—for example, Dove and Simple Truth soaps made some (but not all) subjects more enticing, while Native soap seemed to decrease people’s allure.
Contrary to expectations, a soap’s chemical content may be less important than how those contents react with the individual body chemistry of the person using it. “All the soaps we used were largely dominated by a compound called limonene, which is a known mosquito repellent—but three out of four soaps actually increased mosquito attraction,” says Clément Vinauger, a neuroethologist at Virginia Tech and a co-author of the study.
The same chemical, therefore, can be attractive or repulsive to mosquitoes depending on its concentration and how it’s combined with other natural chemicals present on human skin. In nature, Vinauger speculated, maybe one combination of chemicals is interpreted by the mosquito as a “plant” while a different ratio of the same components might scream, “human.”
In the next phase of the personal products study, the researchers analyzed the nylon sleeves from the initial experiment to pick out combinations of chemicals associated with mosquito attraction and repulsion. With this data, they designed an attractive mix and a repellent mix and tested them with a fifth subject, who was not a part of the previous experiments.
When given a choice between a sleeve spiked with the attractive mix and a sleeve spiked with mineral oil (the control), mosquitoes overwhelmingly favored the attractive mix, says Chloé Lahondère, an entomologist at Virgina Tech and a co-author of the study. Similarly, mosquitoes preferred to land on the sleeve with mineral oil when the repellent mix was offered.
How mosquitoes use other senses
Mosquitoes are scarily adept at finding us, and research in the past year has provided some clues as to why. The upshot? They're flexible, adaptable, and resilient. "For any given task, mosquitoes are constantly integrating multiple sources of information: visual, olfactory, acoustic, and thermal," Vinauger says.
According to a recent paper, for example, mosquitoes can "see" infrared radiation, joining the short list of animals capable of detecting it. They also tune their vision depending on what they're smelling. Human odors make mosquitoes more sensitive to skin tone colors, for instance, while floral odors prime them to see colors associated with plants.
And much like a visually-impaired person with a heightened sense of hearing, when one sense gets knocked out, others are enhanced to compensate.
Take a mosquito's sense of smell, for example. When scientists disabled A. aegypti mosquitoes' olfactory system, located primarily on their head, they became better at sensing heat. In research published earlier this year, mosquitoes genetically engineered to lack olfactory receptors—which bind to odor molecules, triggering a neural response—were more likely than normal mosquitoes to land on a pad heated to human body temperatures. Additional work showed that these mutants upped the number of temperature-sensitive receptors in the sensory organs in their forelegs.
To Takeshi Morita, one of the study's authors, this information can help boost both our defense and offense. "When designing repellants or traps, we need to simultaneously disrupt multiple sensory modalities to effectively fight these deadly and persistent predators of humans," he says. He hopes to test whether other senses—like the ability to detect humidity—are also super-charged when mosquitoes can't smell.
But the most transformative advance, according to Vinauger, is the publication of the mosquito's single-cell genetic atlas, which iscurrently under peer review. By identifying which genes are expressed in each cell, scientists have a map that will help them understand the function of specific organs and tissues.
"We can really dive in and tease apart what's going on in each cell type," Vinauger says. He compares it to working with a blunt instrument versus working with a micro-scalpel.
The best ways to repel mosquitoes
Research to devise fail-safe repellents is still in its infancy, but scientists have some preliminary ideas based on the current science. Try products with a coconut scent, the aroma associated with the soap that more consistently deterred mosquitoes, Vinauger suggests. “And since it might depend on your personal body odor, experiment with different soaps to see which one works best.”
(See our picks for the best mosquito repellents, from sprays to lotions.)
But the best defense we have against mosquitoes remains traditional repellents like DEET, which experts recommend if you plan to be in regions where mosquito-borne illnesses are endemic. Natural repellents like lemon eucalyptus oil can also work, but they’re much less effective and must be reapplied more often.
DeGennaro, who lives in Florida, recalls, “During the Zika phase, I would wear DEET every day.” It’s safe when used as directed and it also works great on ticks, he adds.
(Keep mosquitoes away with these simple tips, backed by science.)
As for Zarins, she can’t wait for the day when she can hang up her hat as her son’s personal mosquito magnet and find a repellant that works for both of them.
