# Why Mosquitoes Bite Some People More: CO2, Odor, Heat, Color

> Why mosquitoes bite some people more than others, based on studies of carbon dioxide, skin odor chemistry, heat, clothing color, pregnancy, beer, and blood type claims.

Source: https://longsleeve.com/blog/why-mosquitoes-bite-some-people

By [Andrew Rothaus](https://longsleeve.com/about), Founder · August 6, 2026 · Updated August 16, 2026

Mosquitoes find you with carbon dioxide first, then vision, then heat and skin odor up close. The strongest evidence for why one person gets bitten more than another points to body odor chemistry, especially carboxylic acids produced by skin and skin bacteria. That trait appears stable for years and has a genetic component.

## How does a mosquito find a person?

Only female mosquitoes bite, because they "need a blood meal to produce eggs," per the CDC, which also describes the sensing hardware: antennae are "long feather-like organs that detect carbon dioxide from a person's breath and movement of air," palps "sense odor," and mosquitoes "have two large compound eyes that detect movement."

**Short answer:** Mosquitoes use carbon dioxide, vision, heat, and skin odor to find people. The strongest evidence for why one person gets bitten more than another points to skin odor chemistry, especially carboxylic acids associated with skin and skin bacteria. Carbon dioxide helps mosquitoes find the neighborhood; skin odor helps them choose the address.

## Is carbon dioxide why some people get bitten more?

Probably not on its own. CO2 switches the system on, but it is a generic animal signal. A 2021 review in Current Research in Parasitology and Vector-Borne Diseases notes that output varies with "metabolic rate, body mass and respiratory activity," then gives the counterargument: "it is unlikely that the variation in attractiveness to mosquitoes is due to differential production of CO2 or lactic acid precisely because of their generalist characteristics." Van Breugel's team cited work showing that given separate plumes, "Aedes followed the skin volatiles rather than the CO2." Breath gets them to the neighborhood. Skin picks the address.

## What does the strongest evidence say about body odor?

The best data lives here. In a 2022 Cell paper, De Obaldia and colleagues at Rockefeller University "identified people who are exceptionally attractive or unattractive to mosquitoes." NIH described the setup: "Sixty-four volunteers wore nylon sleeves on their arms for six hours." In a round-robin among eight subjects, the top scorer had "4 times the attractiveness score of the next most attractive subject, and over 100 times greater than that of the two least attractive," and "these differences were stable over several years." The chemistry pointed one direction: "highly attractive people produce significantly more carboxylic acids in their skin emanations," specifically pentadecanoic, heptadecanoic and nonadecanoic acids plus ten unidentified compounds in that class.

The limits matter just as much. Per NIH, the study "could not show whether high levels of carboxylic acids were directly driving mosquito preference, only that they were associated with attractiveness." The blend varied between people, so "there may be more than one way for a person to be highly attractive to mosquitoes," and one subject with high carboxylic acid levels was only weakly attractive. Context matters too: preference only shows up when mosquitoes have options, and someone alone in an infested area "may receive many bites, regardless of their overall attractiveness level because they are the only feeding option."

## Do skin bacteria matter?

Yes, on narrower evidence. Verhulst and colleagues, in PLoS ONE in 2011, tested 48 men against *Anopheles gambiae* and found that highly attractive individuals "have a significantly higher abundance, but lower diversity of bacteria on their skin than individuals that are poorly attractive." *Staphylococcus* was 2.62 times more abundant in that group. The Cell team noted the link: "skin bacteria contribute to the pool of free fatty acids found on human skin," and skin microbiota is "remarkably stable within an individual over time."

## Is being a mosquito magnet genetic?

Partly. Fernández-Grandon and colleagues tested identical and non-identical twins against [Aedes aegypti](https://longsleeve.com/blog/aedes-aegypti) in PLoS ONE in 2015. Identical twin pairs "showed a high correlation in attractiveness to mosquitoes, while non-identical twin pairs showed a significantly lower correlation," giving "a strong narrow-sense heritability of 0.62 (SE 0.124) for relative attraction" and demonstrating "an underlying genetic component."

## Does clothing color matter?

There is real lab evidence, with a catch: color only counts once the mosquito has smelled CO2. A 2022 Nature Communications study tracked 1.3 million *Aedes aegypti* trajectories in a wind tunnel and found that "when encountering odor, mosquitoes become particularly attracted to hues that are dominant in human skin," in the long-wavelength range of 590 to 660 nanometers. Blocking those wavelengths "can suppress object attraction." Contrast registered too, with "mosquitoes investigating and preferring darker objects." High-contrast dark clothing is a modest lever at best.

## Do mosquitoes prefer certain blood types?

This is the weakest claim in the canon. The most-cited supporting study, Shirai and colleagues in the Journal of Medical Entomology in 2004, is more equivocal than its reputation: blood group O subjects "attracted more Aedes albopictus than other blood groups (B, AB, and A) but were only significantly more attractive than blood group A subjects in 64 human landing tests." Applied directly to forearm skin, ABH antigens "did not, in general, influence the landing preference of mosquitoes among ABO blood groups."

The 2021 review is blunter: the suggested association "was later refuted." A 2021 Scientific Reports paper on blood type and host-seeking in *Anopheles stephensi* was retracted in June 2022, the note citing "errors and discrepancies that could not be resolved."

## Does beer make you more attractive to mosquitoes?

Two small studies say yes. Shirai and colleagues, in the Journal of the American Mosquito Control Association in 2002, tested 13 volunteers who drank 350 ml of beer and found landing "significantly increased after beer ingestion compared with before ingestion," though "ethanol content in sweat and skin temperature did not show any correlation." Lefèvre and colleagues ran a larger test in Burkina Faso, in PLoS ONE in 2010: 25 volunteers drank a litre of local sorghum beer, 18 drank water. "Water consumption had no effect on human attractiveness to An. gambiae mosquitoes, but beer consumption increased volunteer attractiveness," with orientation toward the odor trap rising to 65 percent against roughly 47 to 53 percent otherwise. Once again, "the level of exhaled carbon dioxide and body temperature had no effect."

All 43 volunteers were Burkinabe men aged 20 to 43, and the drink was one litre of dolo, a sorghum beer of roughly 3 percent alcohol. The 2021 review's read is measured, that "there is some evidence showing that beer consumption could be a risk factor for mosquito bites," and wine and spirits remain untested.

## Are pregnant women bitten more?

Yes, with field data behind it. Lindsay and colleagues, in The Lancet in 2000, studied 12 groups of women over three nights in The Gambia and found that "pregnant women attracted twice the number of Anopheles gambiae complex, the predominant African malaria-carrying mosquito, than did their non-pregnant counterparts," 6.33 per night against 3.1. They identified "increased heat and increased release of volatile substances from the skin surface." The 2021 review adds a behavioral factor: pregnant women "come out from under mosquito nets more often to urinate at night." If you are pregnant, take repellent questions to your clinician.

## What about garlic and vitamin B?

Neither works. The 2021 review states that "contrary to popular belief, garlic and vitamin B, have no apparent effect as repellents." A controlled study found "no effect of vitamin B supplementation," and garlic showed nothing as an *Aedes aegypti* repellent "in a double-blinded, placebo-controlled trial involving humans." A 2018 study did find bananas increased attractiveness to *Anopheles* while green grapes did not, but the review cautions that "the literature on these aspects is quite scarce."

## What does the CDC recommend for preventing mosquito bites?

The CDC recommends EPA-registered insect repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone, and advises looking for "an EPA registration number (EPA Reg. No.) on the insect repellent product label." The rest of its list: loose-fitting long-sleeved shirts and pants, permethrin-treated clothing and gear never applied to skin, window screens kept in repair, air conditioning if available, and weekly emptying of anything holding water. The EPA runs a searchable database of registered skin-applied repellents and is explicit that "EPA and the U.S. Government do not endorse any product or service." If ticks concern you too, see [when tick season runs](https://longsleeve.com/blog/tick-season-when).

## When should you see a doctor about a bite?

The CDC explains that as a mosquito feeds "it injects saliva into your skin. Your body reacts to the saliva resulting in a bump and itching." More severe reactions can occur in children, in adults bitten by unfamiliar species, and in people with immune system disorders, with signs including large swelling, low-grade fever, hives, and swollen lymph nodes. The CDC says not to scratch bites and to "see a healthcare provider if symptoms worsen."

## Where Longsleeve fits

Longsleeve is an EPA-registered picaridin lotion (EPA Reg. No. 101457-1). It repels mosquitoes and ticks for up to 14 hours. It is fragrance-free, with nine disclosed ingredients. Full ingredient details are on our [facts page](https://longsleeve.com/facts).

## Common questions

**Do mosquitoes really prefer type O blood?**

No. The most-cited study found blood group O subjects attracted more Aedes albopictus than group A subjects only, and ABH antigens applied to skin did not generally change landing preference. A 2021 review says the association "was later refuted," and a 2021 Scientific Reports paper on it was retracted in 2022.

**What is the best-supported reason one person gets bitten more than another?**

Skin odor chemistry. A 2022 Cell study found that people exceptionally attractive to Aedes aegypti produce significantly more carboxylic acids in their skin emanations, with a gap of more than 100-fold between the most and least attractive volunteers that held for years. It showed association, not causation.

**Does holding still or holding your breath help?**

Not much. Mosquitoes detect carbon dioxide and air movement with their antennae, odor with their palps, and movement with their compound eyes. CO2 detection switches on their attraction to visual features.

**Can I change how attractive I am to mosquitoes?**

The core trait looks stable. Researchers proposed that exceptionally high or low attractiveness is a "fixed" trait caused by factors constant over several years, and a twin study reported narrow-sense heritability of 0.62 for relative attraction. Pregnancy and, in two small studies, beer do appear to shift it. For personal guidance, talk to your clinician.

## Related reading

- [How to Treat a Mosquito Bite](https://longsleeve.com/blog/mosquito-bite-treatment). Why bites itch, what helps, and when to see someone.
- [The Asian Tiger Mosquito](https://longsleeve.com/blog/asian-tiger-mosquito). A daytime biter that breeds in whatever holds water.
- [Our field guide to biting insects](https://longsleeve.com/facts). The sourced field guide: species, ranges, and the diseases they carry.
- [Do Ultrasonic Repellers Work?](https://longsleeve.com/blog/ultrasonic-repellers). Why sound does not do what the packaging claims.

More Longsleeve in your Google feed:

## Sources

1. CDC, About Mosquitoes. [https://www.cdc.gov/mosquitoes/about/index.html](https://www.cdc.gov/mosquitoes/about/index.html)
1. CDC, About Mosquito Bites. [https://www.cdc.gov/mosquitoes/about/about-mosquito-bites.html](https://www.cdc.gov/mosquitoes/about/about-mosquito-bites.html)
1. CDC, Preventing Mosquito Bites. [https://www.cdc.gov/mosquitoes/prevention/index.html](https://www.cdc.gov/mosquitoes/prevention/index.html)
1. EPA, Find the Repellent that is Right for You. [https://www.epa.gov/insect-repellents/find-repellent-right-you](https://www.epa.gov/insect-repellents/find-repellent-right-you)
1. van Breugel F, Riffell J, Fairhall A, Dickinson MH. Mosquitoes Use Vision to Associate Odor Plumes with Thermal Targets. Current Biology, 2015. [https://pmc.ncbi.nlm.nih.gov/articles/PMC4546539/](https://pmc.ncbi.nlm.nih.gov/articles/PMC4546539/)
1. De Obaldia ME, Morita T, Dedmon LC, Boehmler DJ, Jiang CS, Zeledon EV, et al. Differential mosquito attraction to humans is associated with skin-derived carboxylic acid levels. Cell, 2022. [https://pmc.ncbi.nlm.nih.gov/articles/PMC10069481/](https://pmc.ncbi.nlm.nih.gov/articles/PMC10069481/)
1. NIH Research Matters, Skin compounds associated with attractiveness to mosquitoes, November 1, 2022. [https://www.nih.gov/news-events/nih-research-matters/skin-compounds-associated-attractiveness-mosquitoes](https://www.nih.gov/news-events/nih-research-matters/skin-compounds-associated-attractiveness-mosquitoes)
1. Verhulst NO, Qiu YT, Beijleveld H, Maliepaard C, Knights D, Schulz S, et al. Composition of Human Skin Microbiota Affects Attractiveness to Malaria Mosquitoes. PLoS ONE, 2011. [https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0028991](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0028991)
1. Fernández-Grandon GM, Gezan SA, Armour JA, Pickett JA, Logan JG. Heritability of Attractiveness to Mosquitoes. PLoS ONE, 2015. [https://pmc.ncbi.nlm.nih.gov/articles/PMC4406498/](https://pmc.ncbi.nlm.nih.gov/articles/PMC4406498/)
1. The olfactory gating of visual preferences to human skin and visible spectra in mosquitoes. Nature Communications, 2022. [https://www.nature.com/articles/s41467-022-28195-x](https://www.nature.com/articles/s41467-022-28195-x)
1. Ellwanger JH, Cardoso JDC, Chies JAB. Variability in human attractiveness to mosquitoes. Current Research in Parasitology and Vector-Borne Diseases, 2021. [https://pmc.ncbi.nlm.nih.gov/articles/PMC8906108/](https://pmc.ncbi.nlm.nih.gov/articles/PMC8906108/)
1. Lindsay S, et al. Effect of pregnancy on exposure to malaria mosquitoes. The Lancet, 2000. [https://pubmed.ncbi.nlm.nih.gov/10859048/](https://pubmed.ncbi.nlm.nih.gov/10859048/)
1. Lefèvre T, Gouagna LC, Dabiré KR, Elguero E, Fontenille D, Renaud F, et al. Beer Consumption Increases Human Attractiveness to Malaria Mosquitoes. PLoS ONE, 2010. [https://pmc.ncbi.nlm.nih.gov/articles/PMC2832015/](https://pmc.ncbi.nlm.nih.gov/articles/PMC2832015/)
1. Shirai Y, et al. Alcohol ingestion stimulates mosquito attraction. Journal of the American Mosquito Control Association, 2002. [https://pubmed.ncbi.nlm.nih.gov/12083361/](https://pubmed.ncbi.nlm.nih.gov/12083361/)
1. Shirai Y, et al. Landing preference of *Aedes albopictus* (Diptera: Culicidae) on human skin among ABO blood groups, secretors or nonsecretors, and ABH antigens. Journal of Medical Entomology, 2004. [https://pubmed.ncbi.nlm.nih.gov/15311477/](https://pubmed.ncbi.nlm.nih.gov/15311477/)
1. Khan SA, Abu Kassim NF, Webb CE, Aqueel MA, Ahmad S, Malik S, Hussain T. Retraction Note: Human blood type influences the host-seeking behavior and fecundity of the Asian malaria vector *Anopheles stephensi*. Scientific Reports, June 17, 2022. [https://www.nature.com/articles/s41598-022-14546-7](https://www.nature.com/articles/s41598-022-14546-7)

Last reviewed 2026-08-06 · every claim on this page is sourced above

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