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The surprising science behind why mosquitoes seem to prefer some people over others.
Every summer, our family gathered at my in-laws’ house. After a hot day, we would open the living room windows—there were no screens—to let the cool evening breeze flow through the house. It was one of those simple family moments we all looked forward to.
It never took long.
Soon, we would notice two or three mosquitoes buzzing around the room. Before long, everyone would start scratching their arms and legs.
Everyone… except my father-in-law.
Even when a mosquito landed on his arm, it often seemed to fly away without biting him. Meanwhile, the rest of us kept swatting mosquitoes and wondering why they always seemed to choose us instead.
Smiling, my mother-in-law would look at him and say,
“You must have something in your blood that keeps the mosquitoes away.”
We all laughed because it sounded like one of those family myths.
Today, both of my in-laws have passed away, but those warm summer evenings remain among my favourite family memories. Every mosquito bite still reminds me of the question we asked so many years ago.
What makes me smile is that my mother-in-law’s joke was, in a way, surprisingly close to what scientists have discovered.
Mosquitoes really do choose some people over others.
Not because of “sweet blood” or bad luck, but because they respond to an invisible combination of body chemistry, skin bacteria, body temperature, breathing, and many other biological signals that make each of us unique.
So why are some people mosquito magnets while others seem almost invisible? In other words, why do mosquitoes bite some people more than others?
Let’s look at what science has uncovered.
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Mosquitoes Don’t Bite Everyone
The first surprise is that not every mosquito is interested in humans.
Scientists have identified more than 3,500 mosquito species worldwide. Many never feed on humans. Some specialize in feeding on birds, reptiles, amphibians, or other mammals, while a few species never feed on blood at all.
Only a relatively small number of mosquito species have evolved to specialize in biting humans. Among these are Aedes aegypti, responsible for transmitting diseases such as dengue and Zika, and several Anopheles species that can transmit malaria.
Even among these human-biting mosquitoes, not everyone is equally attractive.
Research consistently shows that some people receive significantly more bites than others.
So how do mosquitoes make that choice?
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How Do Mosquitoes Find You?
Contrary to popular belief, mosquitoes are not searching for blood.
They are searching for you.
Long before a mosquito lands, it has already begun gathering information.
The first clue is carbon dioxide (CO₂), which we release every time we breathe. Mosquitoes can detect tiny increases in carbon dioxide from several metres away.
As they fly closer, they begin collecting more information.
They detect:
- your natural skin odours,
- body heat,
- moisture around your skin,
- movement,
- visual contrast,
- and even the warmth radiating from your body.
Rather than relying on a single signal, mosquitoes combine all these clues before deciding whether to land.
Think of it as solving a puzzle rather than following a single scent.
But finding a person is only half the challenge.
When several people are sitting together—as we were during those summer evenings at my in-laws’ house—the mosquitoes have already found everyone in the room.
The real question is:
Why do they decide to bite one person and ignore another?
The answer lies in something we cannot see.
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Your Skin’s Invisible Has Its Own Chemical Fingerprint
Although we usually think of our skin as simply covering our bodies, it is constantly releasing hundreds of tiny airborne molecules called volatile organic compounds (VOCs).
Some of these compounds are produced naturally by our bodies.
Others are produced by the billions of harmless bacteria that naturally live on our skin. As these bacteria break down sweat and skin oils, they create additional chemicals that become part of our natural scent.
Together, these compounds create an invisible chemical fingerprint that is unique to every person.
One of the most important discoveries in recent years came from a 2022 study published in Cell. Researchers found that people who consistently attracted the most mosquitoes produced much higher levels of specific compounds called carboxylic acids.
A 2025 review further explained that our skin microbiota—the community of microorganisms living on our skin—plays a major role in shaping these chemical fingerprints. In other words, mosquitoes are often responding not only to you, but also to the microscopic organisms that naturally live on your skin.
This helps explain why some people seem to be mosquito magnets throughout their lives.
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Why Do Mosquitoes Prefer Some People?
Scientists have identified several factors that can influence mosquito attraction.
Body Size
Larger individuals generally produce more carbon dioxide simply because they breathe more air. They also generate more body heat, release larger amounts of skin odours, and present a larger visual and thermal target.
From a mosquito’s perspective, they are simply easier to detect.
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Physical Activity
This section finally answered one of my own questions.
I had noticed that after working in the garden, mosquitoes seemed to find me much faster.
The explanation is surprisingly simple.
Physical activity increases:
- breathing rate,
- carbon dioxide production,
- perspiration,
- body temperature.
These are exactly the signals mosquitoes use to locate a host.
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Pregnancy
Pregnant women are known to attract significantly more mosquitoes than non-pregnant women.
Researchers believe several physiological changes contribute to this increased attractiveness.
Pregnant women:
- exhale approximately 21% more air,
- have slightly higher body temperatures,
- experience hormonal changes,
- release different skin odours.
Together, these changes make them easier for mosquitoes to detect.
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Age
Some studies suggest that children are more attractive to certain mosquito species than adults.
Scientists believe differences in skin bacteria, body chemistry, and body temperature may explain these observations.
However, this relationship appears to vary depending on the mosquito species, so research continues.
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Does Blood Type Matter?
This is probably one of the most common questions people ask.
Some studies have suggested that mosquitoes land more frequently on people with blood type O. However, other studies have found no significant difference.
After reviewing all the available evidence, scientists conclude that the relationship between blood type and mosquito attraction remains unclear. Any effect appears to depend on the mosquito species and is much smaller than differences in body odour and skin chemistry.
So, if you always seem to be the one mosquitoes choose, your blood type is probably only a small part—if any—of the explanation.
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Can Food or Drinks Make a Difference?
Research suggests that drinking alcohol, particularly beer, can increase mosquito attraction.
Interestingly, this increase does not appear to result from higher body temperature or greater carbon dioxide production. Instead, alcohol seems to alter the body’s natural odour.
Some small studies have also suggested that eating bananas may increase mosquito attraction, although the evidence is still limited and requires further research.
On the other hand, despite their popularity as home remedies, there is currently no convincing scientific evidence that eating garlic or taking vitamin B supplements protects against mosquito bites.
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What About Perfume or Showering?
This was another question I often wondered about.
Could wearing perfume make me more attractive to mosquitoes? What about showering?
The answer is more complicated than a simple yes or no.
Mosquitoes don’t respond to pleasant smells the way humans do. Instead, they detect specific chemical compounds.
Some perfumes contain floral ingredients that resemble compounds mosquitoes naturally encounter while feeding on nectar. Others may partially mask our natural body odours or even contain ingredients mosquitoes find less attractive.
Similarly, there is no evidence that showering itself attracts mosquitoes.
However, freshly applied soaps, lotions, deodorants, or perfumes temporarily change the mixture of chemicals released by our skin. Combined with warmer skin after a shower, these changes may influence how mosquitoes perceive us.
Scientists are still investigating exactly how personal care products affect mosquito attraction.
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So… Was My Mother-in-Law Right?
I still don’t know exactly why mosquitoes almost always ignored my father-in-law.
But science offers a fascinating explanation.
Every person releases a unique combination of skin chemicals, microbial by-products, body heat, moisture, and carbon dioxide.
Some combinations are highly attractive to mosquitoes.
Others appear much less interesting.
Perhaps my mother-in-law’s joke wasn’t entirely a joke after all.
She thought there was “something in his blood.”
Science suggests there really was something unique about him—but it wasn’t his blood.
It was the invisible chemistry surrounding his skin.
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The Take-Home Message
Whenever mosquitoes find me first, I still think about those warm summer evenings at my in-laws’ house, the open windows, the cool breeze after a hot day, and my mother-in-law smiling as she teased her husband:
“You must have something in your blood that keeps the mosquitoes away.”
She couldn’t have known that scientists would one day discover just how close her joke was to the truth.
It wasn’t really his blood.
It was the remarkable chemistry of his body.
And perhaps that’s what makes science so fascinating. It often begins with an everyday observation, followed by a simple question:
Why?
If you enjoy discovering the hidden science behind everyday observations, you may also enjoy our article on how plants communicate with one another.
,https://stemtutorex.com/blog/hidden-connections-in-nature/
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References
- De Obaldia, M. E., et al. (2022). Cell. DOI: https://doi.org/10.1016/j.cell.2022.09.034
- Wolff, G. H., & Riffell, J. A. (2018). Olfaction, Experience and Neural Mechanisms Underlying Mosquito Host Preference. Journal of Experimental Biology, 221. https://doi.org/10.1242/jeb.157131
- Yan, J., Gangoso, L., Ruiz, S., et al. (2021). Understanding Host Utilization by Mosquitoes: Determinants, Challenges and Future Directions. Biological Reviews, 96, 1367–1385.
- 2025 Review: Mosquito Host Preference: A Review of Host Attractiveness and Influencing Factors.