Why Some People Attract More Mosquitoes Than Others

Some people can stand outside on a summer evening and walk back in without a single bite. Others get absolutely devoured. It turns out this isn’t bad luck or imagination. Mosquitoes appear to be responding to different chemical and microbial cues on each person’s skin. A new study tested 119 people against three different disease-carrying mosquito species, Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus, and found something that could reshape how scientists think about mosquito repellents: each species ranked participants differently in the lab, so the person who acts as a magnet for one type may barely register with another.

For years, researchers have known that body odor plays a role in mosquito attraction. Most previous work, though, focused on a single mosquito species at a time, leaving a big question unanswered: do all mosquitoes prefer the same people? According to the research, published in the journal iScience, the answer is mostly no. Different species ranked the same group of people in very different orders of preference, meaning a person who is highly attractive to one species is not necessarily on the menu for another. Among the 119 participants, no one was a top target for all three species, and no one was at the bottom of the list for all three either.

One sex-based difference also stood out. One of the three species, Aedes aegypti, the mosquito that spreads dengue, Zika, and yellow fever, showed a slight but statistically significant preference for male participants over female ones, a pattern the other two species did not share.

Who Was Tested and How

Researchers at Florida International University, in collaboration with scientists at the University of Zürich, recruited 119 volunteers from Miami, Florida, aged 18 to 59. Participants were racially and ethnically diverse, and the group was split nearly evenly by sex, with 61 males and 58 females. To keep the results clean, participants were told not to shower the night before their visit and to skip deodorants, perfumes, or scented skin products.

Each volunteer stuck their left forearm into a specially built device, essentially a sealed tube that allowed mosquitoes to respond to a person’s natural scent without any physical contact. For two of the mosquito species, live arms were used. For the third species, Culex quinquefasciatus, a night-biting mosquito that also transmits West Nile virus, participants wore a thin nylon sleeve over their arms for 12 to 16 hours to capture their scent, since those mosquitoes were tested separately under low-light conditions that mimic nighttime.

Three species were tested in total: Aedes aegypti, which primarily targets humans and spreads dengue and Zika; Aedes albopictus, a related species with a broader diet that spreads similar viruses; and Culex quinquefasciatus, the night-biting species associated with West Nile virus. Across all 119 participants, Aedes aegypti showed the highest average attraction rate at about 89%, Culex quinquefasciatus came in around 43%, and Aedes albopictus had the lowest average at about 27%. These differences in overall enthusiasm for humans may reflect how deeply each species has evolved to rely on human blood, though the study’s design does not directly establish that connection.

What Mosquitoes Are Actually Smelling

To figure out what made certain people more or less attractive, the research team collected the invisible cloud of chemicals coming off each participant’s arm and analyzed it to identify individual compounds. At the same time, they swabbed participants’ forearms to study the bacteria on their skin, cataloging 246 distinct bacterial taxa across the 119 participants.

Only one of those taxa appeared in every participant, a notable result given how much the skin’s microbial makeup varies from person to person. That variability, the researchers argue, is a key part of why mosquitoes respond so differently to different people.

For Aedes aegypti, the dengue-and Zika-spreading species, high attraction was closely linked to Staphylococcus bacteria on the skin, a pattern specific to this species and consistent with earlier research. People who were least attractive to this species tended to have more Pseudomonas bacteria on their arms, a pattern previously associated with reduced mosquito attraction. When it came to airborne chemicals, high attraction for this species was tied to the absence of certain compounds rather than the presence of appealing ones, hinting that these mosquitoes may home in on people who simply lack natural deterrents.

For Aedes albopictus, the broader-diet species, the pattern flipped. High attraction was linked to the presence of specific appealing chemicals, including one compound previously tied to how mosquitoes evolved a preference for humans in the first place. Researchers found 13 volatiles were more common among people who scored highly on attraction to this species, compared with just one such chemical for Aedes aegypti. That broader set of appealing odors aligns with this mosquito’s more opportunistic nature, since it feeds on a wider range of animals rather than specializing on humans.

For Culex quinquefasciatus, the night-biting, West Nile-associated species, high attraction was again tied more to the absence of certain compounds than to the presence of appealing ones. No bacterial species were significantly linked to high attraction here, though bacteria in the Actinomyces group were associated with low attraction.

Why This Research Could Change Mosquito Repellents

Digging into why males drew more Aedes aegypti, the researchers found that male participants carried higher levels of certain chemicals and bacteria linked to stronger attraction, while female participants carried more of the compounds and microbes this species found less appealing. The team was careful to note that the study was not large enough to draw firm conclusions about race or ethnicity and mosquito attraction. Any differences observed in the data should be treated as limitations rather than as established findings, since the sample size was too small to properly address that question.

One of the most practical takeaways from the study is what it hints about future mosquito repellents. Right now, most repellent strategies are built on a one-size-fits-all approach. But if different mosquito species are drawn to entirely different chemical and bacterial profiles, a single repellent formula may not work equally well against all of them. The authors raise this point, though the study does not directly test it, as no repellents were evaluated.

By identifying the bacteria and chemicals linked to high attraction for each species, the authors argue that their findings could help guide the development of targeted, biology-based repellents, ones that either produce compounds that actively deter mosquitoes or suppress the skin bacteria that make a person smell appealing in the first place.

Mosquitoes are responsible for more human deaths than any other animal on the planet, and the three species studied here rank among the most medically significant. With all three species predicted to expand their ranges across the Americas, it is urgent to pin down the precise signals that guide them to specific human hosts. This study doesn’t solve that problem, but it gives researchers a much clearer picture of the signals involved.

Disclaimer: This article summarizes findings from a peer-reviewed study and is intended for general informational purposes only. It is not medical or public health advice. The research describes associations between skin bacteria, body odor, and mosquito attraction; it did not test repellents or establish that changing skin bacteria prevents bites. Individual results vary, and readers with concerns about mosquito-borne illness should consult a qualified health professional or local health authority.

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