Why Do Mosquitoes Bite Some People More Than Others?

Two people sit on the same porch at dusk. One goes inside with a dozen bites, the other never swats once. It feels like a personality trait, and it turns out to be close to one: how appealing you are to a mosquito is a fairly stable property of your own skin chemistry, and part of it is inherited.

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The approach: breath first, then you

Only female mosquitoes bite, because they need blood to develop eggs. They start by sensing the carbon dioxide in your breath from a distance, then home in on warmth and the odor of your skin. Everybody breathes and everybody is warm, so that part of the sequence doesn't separate one person from another. In fact, when researchers knocked out the carbon dioxide receptor in yellow fever mosquitoes, the mutants were only slightly less drawn to live humans in a large semi-field enclosure. Heat and skin odor were enough to carry them to a person (McMeniman et al., Cell, 2014).

That makes skin odor the deciding step, and it is where people really differ.

The "mosquito magnet" is real, and it is steady

A research team tested human skin odor against mosquitoes and found people who were exceptionally attractive and others who were exceptionally unattractive. The ranking was stable over several years. Chemical analysis showed the attractive group made significantly more carboxylic acids in the oils on their skin (De Obaldia et al., Cell, 2022). So the idea that "they just like me" is a fair description of a measurable difference, not folklore.

Genetics plays a part too. A twin study had mosquitoes choose between odors from the hands of identical and non-identical twins. Identical twins matched each other closely in how attractive they were, non-identical twins much less so, and the authors estimated a heritability of 0.62 for relative attraction (Fernandez-Grandon et al., PLoS One, 2015). Put plainly, a good share of the difference you see between you and your friends may have been settled before any of you were born.

What blood type does and doesn't do

You may have read that type O gets bitten most. The study behind that claim used 64 landing tests with Asian tiger mosquitoes. Type O drew more landings than the other groups, but the difference was statistically significant only against type A, and the authors concluded that the blood group antigens they tested did not generally steer landing preference (Shirai et al., Journal of Medical Entomology, 2004). It's a nice party fact, and not a reliable way to predict who will itch tomorrow. Our roundup of mosquito repellent myths takes on the other popular explanations.

What you can take from this

If you are the favorite, none of it is a flaw. Notice the pattern: who in your group gets bitten first, and who never does. Then plan for yourself instead of borrowing a friend's confidence. If you are the person who gets bitten, bring your own repellent and put it on before you go out, not after the first bite.

It also helps to stop comparing. Your friend's bite-free evening says nothing about your own, and arguing about it only makes everyone more annoyed.

Being attractive and being protected are separate questions

You can't change your breath or your genes, and nothing in the research above suggests a food, a soap or a supplement will rewrite your skin odor. What you can change is how many mosquitoes there are and what they meet when they arrive.

Use a registered repellent. EPA says to look for an EPA registration number on the label, which shows the company gave the agency effectiveness data, and to apply and reapply as the label directs. EPA also notes that individual differences in how attractive people are to mosquitoes can affect how a repellent performs, which is one more reason to follow the label to the letter if you are the favorite.
Cover up. Loose long sleeves and long pants put fabric between you and the mosquito.
Drain what holds water. Buckets, saucers and birdbaths make the mosquitoes in the first place. Our backyard guide goes through the weekly routine.

A quick evening checklist for any yard: tip out anything holding water, check that the screens are intact, put on your repellent as the label directs, and cover up before the light fades. None of it is glamorous, and all of it is within your reach.

One clarification, since our name is on a bottle of lemon eucalyptus oil. We sell an essential oil, steam distilled from the leaf, and it is not an EPA-registered repellent. CDC does not recommend using "pure" oil of lemon eucalyptus as a repellent. The registered ingredient is a refined form, explained in our piece on OLE versus the essential oil, and our primer on how mosquito repellents work shows where a registered product steps in. If a child under 3 is involved, or you are pregnant or heading somewhere with mosquito-borne illness, a pediatrician, physician or travel clinic is the right person to choose the product with you.

So if the mosquitoes keep choosing you, take it as a compliment to your chemistry and a reminder to plan around it. Pick a registered product, read its label, and clear the standing water before the evening starts.