Life Science

Why do mosquitoes bite some people more than others?

- asks Allison from Austin

September 10, 2007
Credit: [Oxbow Park Naturalization Project].
Credit: [Oxbow Park Naturalization Project].

Every summer, they come. They sneak through the windows and ravage your ankles; they find the one spot on your left shoulder that didn’t get drenched in a layer of DEET (God bless you, Deep Woods Off!) and gnaw, chomp, and suck away.

From May to September, many of us – covered in scars and bloody scabs, the remnants of these bites now gone bad – live side-by-side with people who, despite living in the same house and even sleeping in the same bed, are seemingly less vulnerable to the vicious six-legged predators. It turns out, a mosquito’s snacking preference for one person over another is not just a curious annoyance, it’s also a medical concern: Since malaria and other diseases are transmitted by bites, people who get bitten a lot are more likely to become ill. Because of this, researchers are working to find the mechanisms in mosquitoes that cause them to sniff out you, and not your neighbor.

Scientists have identified several proteins found in mosquitoes’ antennae and heads that latch on to chemical markers, or odorants, emitted from our skin. These markers are produced by the natural processes of our bodies and, like neon signs, they let the mosquitoes’ smell center know you’re around (though the process that then guides them to you is not well understood). Flies and mosquitoes share a number of the same genes that dictate production of these odorant-binding proteins, which have specific sites that will catch or bind with certain chemicals in the air. Some scientists suggest that certain characteristics attract mosquitoes, thereby leading us to have more bites than others. Some of the top candidates: the amount of carbon dioxide in the breath, pregnancy, body temperature, alcohol and odorant markers based on blood type.

Blood-type markers are chemicals released by people of a specific blood type – so if someone with AB blood emitted a marker, it would be different than that released by B. One study found persons with Type O blood suffered more mosquito landings because of the odorant markers they emit than any other blood type, making their juices a hot commodity for blood banks, as well as Asian Tiger Mosquitoes, which carry West Nile Virus. Not only were Type O’s more likely to be landed on, but the study found that for any blood type, people who secreted a chemical marker about their blood type through their skin (both blood type and secretor status are determined by genes) were bitten much more than non-secretors; 24 percent in the case of the Type O’s. Other researchers estimate about 15 percent of the population, based on their genes, don’t emit chemical markers of their blood type through their skin and saliva, so something else has to be calling the mosquitoes to them.

Pregnancy seems to be a big winner for mosquito attraction, probably because mothers-to-be exhale 21 percent more carbon dioxide (quite a turn-on to the six-legged species) and are on average 1.26 degrees Fahrenheit warmer around the belly than their non-pregnant counterparts, due to the temperature of amniotic fluid. Also, having just 12 ounces of beer increases your mosquito appeal, possibly because of the increase in body temperature it causes or because skin markers change when metabolizing cocktails – unfortunate since outdoor drinking is a highlight of summer anywhere.

One researcher suggested smell is unimportant, and what really matters to the mosquito currently chomping on your toe is not the smells you’re giving off, rather it’s finishing her meal without being swatted away. Because of this, she’s better off attacking “less defensive” animals, rather than more defensive, and so is evolutionarily predisposed to biting lazy or incapacitated prey (reference drinking above).

Infectious disease experts are anxious to solve the mosquito preference puzzle so they can design repellants tailored to vulnerable people, which would either block an individual’s smell signatures or disarm a mosquito’s scent receptors. Unfortunately, a specific answer to your skin-piercing question continues to itch away at scientists, and I suggest stocking up on bug repellant in the meantime.

About the Author



Guadalupe Camacho says:

we are sooooooooooooo vulnerable when the mosquitos and flys and other insects arive in the summer months…….I am 69 and suffer every summer….I am ABpositive blood type…..Help me … does anyone have an answer of cure????

Guadalupe Camacho says:

I am AB positive…………every year I suffer with mosquito bites….anyone out there.. has a cure???? I am the only one that gets bit in a crowd. Lupe. :(

amber says:

I’ve always wondered why I never get bitten by mosquitoes, even when everyone around me is getting chomped away. I knew there had to be some kind of scientific based reasoning and I theorized it had to do with smells, so this is a very interesting read.

kara says:

I do beive everything on here because im the only one wth o- blood n the house and the only one that gets bit and they get bigger than the peoples with out o blood ..

mary says:

The blood type thing cant be right because I used to get bit all my childhood terribly. After I had my first child 29 years ago, I haven’t gotten a single mosquito bite. I figured it had to do with my chemistry changing after pregnancy. I just watched one land on me and move to 6 different spots trying to get a good spot. It never broke skin. I was just going to keep watching til it flew away, which is what they usually do, but my husband asked me to swat it to protect him….they love him.

John says:

Straight up couldn’t be bothered to read the article because your opening pictures is a Mayfly, not a mosquito.
You may want to address that issue. It’ll lend an air of research, knowledge and professionalism to your work.

Msknoitall says:

I can be in a crowd, say at a picnic and i will get eaten alive while others suffer no bites. This happens all the time, so much so that i am hestiant to engage in outside activities and repellants have no affect. Still haven’t a clue how to protect myself. These bites hurt and they ruin your skins!!! I need a defense!

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#11 is an idiot. Here are facts SCIENTIFIC FACTS RESEARCHED and just because it doesn’t happen TO HER she says she’s, “…not buying the blood theory.” What a moron. So if it does not happen to you that’s the way of the world. pfffft. Why is the world full these stupid people?

Chess Risette says:

Whaaaaaaaaaatt? I’m Blood Type A and I usually keeps on getting bitten by mosquitoes more than that of my sister who’s Blood Type O. It’s so frustrating especially during the cold season that mosquitoes are hiding inside the houses and dark places. I’m always the poor one in my family. I have to put ointments everywhere in my body :/

Vijayan Aravamudhan says:

Well, my blood type is B+ positive and get bitten more than others. I often see mosquitoes hovering around me more. It’s messy to use the creams and my main remedy is with a mosquito net that is pretty simple and more practical to me. And yes the ones that attach me inside the net sometimes, face the wrath of my chinese mosquito bat!!

Ryan says:

This is not a picture of a mosquito.

It really is just coincidence rather than blood type It is possible that it was just where you were standing at that moment of popularity of the mosquitos at that time chemicals in blood are tremendous to I get bit even in las Vegas by mosquitoes they itch really bad . Blood type has nothing to do with this. I get bit Simi alot body temputure average of 97.2F my blood type I think is AB+ Positive.

Gerry Olohan says:

I have just read the article, but not all the comments.
My wife was a rare blood type and had terrible trouble
with Mosquitoes until she was diagnosed with Leukaemia
they never went near her again. Can they detect
if the blood is not right?

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the features of antioxidants against cancer before proper suggestions is usually done.
There is greater reason for that you simply
ought to participate. The cancer hospitals in India have well trained staff to worry of cancer patients.

Redwan says:

I am with O+ve. I am a victim of mosquito.

Debra says:

I have B- blood and no one gets bit when I’m around cause all the Mosquitos are chewing on me.

Rich says:

Blood type has nothing to do with bite ratio. My wife and I are both O+ she doesnt get bitten I do. Body temp also out. Both reading same temp, difference between us besides different sexes is I have an extremely high fast moving immune system due to pollen reaction. Being +/-or A,AB,O seems little in bite ratio from reading all the articles seem little to no effect. Maybe we are all looking into this far to much. It is what it is. Chemical inbalance within each of us. Blood impurities she gives blood 4 times a year and it is accepted, I do not give blood as test results came back as not being clean enough to use. No I do not have aids or anything harmful to me it is just not clean enough. Look at the countries reports come in from hygiene not always great and temps are high thrieving areas for insects to increase in. Oh the bloke from the army, hydration theory is out I drink 1 pint water a day my wife 4 pints water a day I still get bitten. You all want possible solution for going out without getting bitten, simple move to north pole insects dont like extreme cold

Stephanie says:

I’m not buying the blood type causing more bites. My DH is Type O- and never gets a bite. I am A+ and get bit on a regular basis. Neither one of us smoke or drink.
I will say that I noticed something interesting this summer though. I have been using different soaps. My normal soap was Irish Spring. Of course I always got bit. I changed to a citrus soap, and I didn’t get bit. I ran out of my citrus on vacation and used a coconut soap, and I got bit again. I also tried an Almond soap and got bit. I finally went back to the citrus, and I don’t get bit. I can’t tell you everthing that attracts mosquitoes, but I can definitely tell you what can help prevent them from sucking your blood….citrus soap. Hope it works for others as well!

Amber says:

I’m type B+ and it seems every day about 2-3 more bites get added to my collection. While other folks say they haven’t seen a mosquito since moving to southern California, I’m a native that’s walking proof that they’re around.. I always say the bugs want happy blood so they go for be positive blood heh

Ekeh kelechi Emmanuel says:

I believe in the temperature points. But u know tastes of meats are not always the same-some are sweeter-even same fruits can differ in taste. When go to buy items or even fishes,chickens…at point and kill you make a choice-select the one that attracts you. So mosquito goes to the sweeter person. Bees do go to flowers that produce more juices to aid formation of honey-all animals have a level of intelligence

Kat says:

Ever since I can remember I’ve had serious reactions to bee stings and mosquitoes. After I had my second child my reaction to the bites we’re not as bad, but I still get eaten alive.

drexel says:

why do mosquitos bite us

drexel says:

my answer to this post is>>>>>>>First of all, it’s not in your head. Mosquitoes really do prefer some people to others, says Dr. Jonathan Day, a medical entomologist and mosquito expert at the University of Florida. And that time your grandmother told you your skin was just sweeter? There’s some truth to that, Day says. “Some people produce more of certain chemicals in their skin,” he explains. “And a few of those chemicals, like lactic acid, attract mosquitoes.” There’s also evidence that one blood type (O) attracts mosquitoes more than others (A or B).

Unfortunately, your genes dictate your blood type and the chemical makeup of your birthday suit. Genetics also determine several other factors that could make you an object of blood-sucking affection for your local mosquito population, Day says. Maybe the most important: Your metabolic rate, or the amount of carbon dioxide (CO2) your body releases as it burns energy.

Mosquitoes use CO2 as their primary means of identifying bite targets, Day says. Why? “All vertebrates produce carbon dioxide, so what better way could there be for a mosquito to cue in on a host?” And while it’s true that you can moderate your metabolic rate through diet and exercise, you can only change your metabolism so much, Day says.

“Pregnant women and overweight or obese people tend to have higher resting metabolic rates, which may make them more attractive to mosquitoes,” he explains. Also, drinking alcohol or physically exerting yourself raises your metabolic rate—and also your appeal to winged biters, he adds. (Exercising before grabbing a beer and heading outside = asking for trouble.)

While CO2 detection is the primary technique mosquitoes and other blood-sucking bugs use to spot hosts, they also rely on secondary cues to differentiate you from cars, decaying trees, and other CO2-producing objects. And you can control some of those secondary cues, Day says.

For example: Dark clothing is more attractive to mosquitoes than light oufits. Why? “Mosquitoes have problems flying in even a slight wind, and so they keep close to the ground,” Day explains. Down there, they spot hosts by comparing your silhouette to the horizon. Dark colors stand out, while light shades blend in, he says. At the same time, lots of motion distinguishes you from your surroundings. So if you’re moving around a lot or gesturing, you might as well be shouting, “Hey, mosquitoes! I’m right here, ladies!” (Only the females bite, Day says.)

Veronica says:

I think it probably has to do with a person’s body PH rather than their blood type. The PH of your blood would actually change the way you taste to the mosquitoes, fleas, etc. I’ve noticed that on the rare occasion I’m bitten by a mosquito, it doesn’t swell up as much if I eat healthy, but as soon as I start eating a bunch of sweets- BIG ITCHY MESS!

Melissa webb says:

Hi I’ve never bin bitten and I honestly think it’s because I’m vodka drinker I no that sounds bad lol but I really believe it’s true x

Carol says:

I’m always the one getting bitten. I am trying home remedies. So far, nothing is working.

Carol says:

I worry about using deet products on a daily basis so I am trying to prepare something safe to apply to my ankles. I will post here if successful. Here is what I plan to try: rubbing alcohol applied to ankles, vinegar applied to ankles. Also wondering if I should buy a dog’s flea collar and wear it on my ankle. Has anyone tried this and is it safe?

Carol says:

I am B negative.

Liset says:

This may be disturbing because I thing those six legged are smart they can sense which person is sick or more sick then the other n that’s who they attack! The weak!

Cal says:

I am 57,white male type O+. Not trying to be different. But I can go into swamps or other areas infested with ticks, fleas and mosquitoes and not have a bite of any kind. As a experiment I placed a tick on my arm and repeatedly it moved to get off of me without attempting to bite. I do not understand why this is but I readily except it. Just wonder if I am not alone in this. ?

curly-01 says:

I’m O+ and I donate blood, so I don’t think its part of blood type. I get bitten like crazy. I also am overweight, yet I exercise 1 hour daily, or at least 3x a week. It doesn’t matter if I use repellents, I’ve watch what I eat, I can run a mile, they just love me. I think its hormonal.

Rubygal says:

My son is 11 and has never been bitten. His twin sister gets eaten alive. We have always wondered why.

Gordon Waite says:

Reading all your posts, being a lifelong victim of mosquitos and being an RN, the article and the comments lead me to believe it is probably based on hormones (women stated that the biting changed after the birth of a child when women’s hormones go through a big change). There does not seem to be blood type specific based on all your comments. It could be the theory of the secretor theory! Since 15% of us are not secretors that could explain the low percent of us that say they do not get sucked on. I am an O negative secretor and am a life time victim of mosquitos.

Dan says:

I don’t normally get bitten, always thought it was to do with the fact that the odour my body gives off when I sleep smells more like a dead, rotting animal than a live one. I binge drink and smoke which causes a stench when my body is cleaning my system after a binge.

Julie Durfee says:

I am O negative . I never ger mosquito bites. They don’t like me and if they land on me they don’t stay long if I get bit I don’t get a bump. However I’ve seen ticks jump twards me. If I go hiking I never leave the trail and come home with them on my neck. They like that spot l. They were also

padma says:

I completely agree with this excellent article. My blood type is O+ n i am only one who is getting bitten by the mosquitoes in crowd.I was actually shocked by reading the article.Damn useful one.

Richy Norman says:

I am a 52 year old white male.My blood type is O+.I very rarely get bitten and have been like this as long as i can remember.Even if i do get bitten i am never left with a mark or a feeling of itchyness.I have put on a huge amount of weight in the last few years,wear dark clothing and still do not get bitten.I used to drink but don’t drink now and that also has made no difference.I am the same with fleas that normally leave me alone but if i do get bitten,i am never left with any mark of the bite..My wife and daughter on the other hand suffer immensely and will scratch and scab up.I thought they were weird.It seems i am the strange one.

Alicia M. says:

I’m not quite sure what blood type I have, but while hanging outside with friends, I always have more than everyone. One of my friends said it was because of my blood sugar levels…is this true? I don’t know my blood sugar levels, but is this a possibility?

Terry says:

I’m 61, caucasian female, type O+ blood and have been a mosquito feast all my life. They itch immediately and I will scratch and tear them apart til they’re infected! But, that all stopped this year when I discovered two things. 1. If I do get bitten, I immediately wet the area put bentonite clay on it and mist again, then let it dry for awhile. No itch afterward. 2. If I chew a big clove of organic garlic (approx. 15 min. before going out) and hold it in my mouth swishing it for as long as I can stand before swallowing it, they leave me alone……but, so does everyone else!

Arletta says:

Then, if it helps you to know, be advised that the reason I ended up on this page was that I was doing research to find out if ill people tend to give off more CO2 than other people. Which was because I had read that bed bugs find you by zeroing in on the CO2 you emit, and, I was having basically zero problems with the ones that other people were getting attacked by, until I got super stressed out which led to me falling ill.

I am not pregnant, I don’t drink alcohol, pretty sure I don’t have type O blood (hard to explain why I am not absolutely sure), but, I do have allergies to things and cortisol issues that lead to illness and I get bit more by bugs, sometimes even bugs that are not known for biting, than mostly anyone, ever, when the illness is upon me. But, when I am not feverish, I get bit basically not at all, ever.

Oh, and, that’s regardless of whether I am ill and laying around or ill and up and moving fast.

Thank you, because, I think you answered my question well enough to give me hope.

Gurpreet says:

I’m blood type A- and mosquitos eat me alive. Just yesterday I went outside to get the mail and came home with 21 bites..couldn’t sleep because the swelling and itching was sooo bad.

John #6 straightup you are so hip. Just don’t know much about insects. Not a mayfly, it’s a CRANE fly!

linda hargreaves says:

I’m O negative and never get bit.. One of the lucky ones

B Kierans says:

I am group O Negative blood and I get bitten all the time.
They even bite me on the same place twice.Hateful bastards.!

Pamela says:

Help, after six months freezing in winter, go in yard, get sting, go to EMERGENCY had to get antibiotics probably hornet, two days later go outside with natural bug ointment, get misquito bite,
Huge, now I’m AFRAID to go in yard! Any suggestion would be appreciated. Do electric zappers work or what other suggestion

Bob says:

I am a 68 yo male who is a heavy cigarette smoker. I attract mosquitos and get bitten frequently. I must have developed some immunity to the types in my area because the itch is moderate and short-lived. The welt usually disappears in an hour or less. When I was young, they were far more severe. However, my feet and legs are a magnet for FLIES! The bite is a sharp sting followed almost immediately by unbearable itching. These are not large deer flies. They look like small house flies. I apply Benadryl or cortisone crème to relieve the itching. 99% DEET seems to be an effective repellant that lasts for an hour or two. I would rather have six mosquito bites than one fly bite. Does my heavy smoking make me more attractive to flies? I have heard from cigarette quitters that they no longer attract mosquitos.

Travis says:

Guadalupe, Since you have AB blood, and you are eaten by mosquitoes, drain your blood and your will be relieved of the mosquito bites.

chris says:

I don’t remember my blood type. when I was a kid i got bitten like a average person now that I got older i can’t remember last time I was bitten, although chiggers sure like bitting me mosquitoes and bed bugs don’t bother I was visiting at friends house i slept on couch 4 nights (friends got bed bugs from a couch that was giving to them) any I seen a bug crawling on are of couch i though it was a roach it was a bed bug the couch had like 20 or 30 bed bugs under the cushion me and my friends boyfriend never got bitten once but my friend she got bitten like every night. I have read that bed bugs do not like acidic blood, maybe mosquitoes are the same way….

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