Mosquitoes and Blood Type: What the Science Says
Mosquitoes do not reliably pick people by blood type. Some studies found that type O gets bitten more, others found type B, and a 2024 review calls the link between blood type and biting ambiguous and dependent on mosquito species and other host factors. If you are the one covered in welts at every cookout, your skin chemistry, your breath and how long you stand outside matter more than the letters on your donor card.
TL;DR
- Type O is the blood type most often named as a mosquito favorite, but the evidence is mixed and depends on the species tested.
- A 2021 lab study of Aedes aegypti found a preference for type B, not type O.
- Carbon dioxide, heat, skin odor, skin bacteria and genetics shape who gets bitten. Blood type is a small piece, if it is one at all.
- Repellent and clothing protect you whatever your blood type. A balm helps after the bite, not before.
- For itching and irritation after a bite, a simple five-ingredient balm is easy to keep in a pack.
Table of Contents
- Where the type O claim comes from
- Studies that disagree with each other
- Do mosquitoes bite people with type A blood?
- What actually makes you a mosquito magnet
- You cannot change your blood type, but you can change your odds
- Our perspective: stop trying to out-think the bite
- Easing the itch when a bite gets through
- Why a short ingredient list matters outdoors
- What the blood type question teaches us about mosquito myths
- FAQ
- Sources
Where the type O claim comes from
The idea is easy to repeat because it sounds tidy. In a 2004 study of Aedes albopictus, the Asian tiger mosquito, researchers counted landings on volunteers of different blood types. Type O volunteers attracted more mosquitoes than types B, AB and A overall, but the difference was statistically significant only against type A. That is a narrower result than “mosquitoes love type O,” which is how it tends to travel online.
Many pest-control and health websites then repeat the claim with more certainty than the studies support. The ranking pages for this topic mostly say type O is the favorite and type A the least favorite. The primary research is less neat.
What a study of one species can and cannot tell you
There are more than 3,000 mosquito species, and the ones that bite people in the United States differ in what they chase. A result in a lab with one species, a small group of volunteers and one way of measuring “attraction” does not carry over to your backyard. Landing on skin, probing and actually feeding are also different behaviors, and studies do not always measure the same one.
Studies that disagree with each other
Here is what the checked research shows:
| Study | Species | What it found |
|---|---|---|
| 2004 landing study | Aedes albopictus | More landings on type O overall, significant only versus type A |
| 2021 laboratory study | Aedes aegypti | Significant preference for type B in five-choice tests; type O blood had the highest digestibility |
| 2021 wind-tunnel study (since retracted) | Anopheles stephensi | Strongest response to type B, type O second |
| 2024 review | Anopheles gambiae | One study found more feeding on type O; a later study using similar methods did not confirm it |
The retracted paper deserves a caution. It reported that mosquitoes fed type B blood laid the most eggs, averaging 216.3 per female, versus 98.01 for type O. Because the paper was retracted, treat those numbers as a curiosity, not a finding. Even by its own account, it covered one malaria-carrying species and should not be read as a rule for people in general.
Being preferred is not the same as being best food
A 2023 review of how host blood affects mosquito reproduction found the effects of blood type contradictory. Some studies suggest a preference for type O, but that preference does not appear to give mosquitoes a reproductive benefit. In other words, even if a mosquito picks you, your blood type may not make you the better meal.
Do mosquitoes bite people with type A blood?
Yes. Every blood type gets bitten. In the 2004 landing study above, type A volunteers drew the fewest landings, and that is the source of the common line that type A is “least attractive.” But the same 2024 review that discusses these studies concludes that the blood type relationship is inconsistent across species. A type A person with a strong odor profile, standing at dusk near standing water, will still get bitten.
What actually makes you a mosquito magnet
If blood type is a weak predictor, what is a strong one? The 2024 review lists several cues mosquitoes use to find a host:
- Exhaled carbon dioxide. It is the long-range signal that tells a mosquito a warm-blooded animal is nearby.
- Heat and visual cues. Mosquitoes home in on warmth and on contrast against the background.
- Odor and skin volatiles. The chemicals your skin releases differ from person to person.
- Skin microbiota. The bacteria on your skin help create your scent.
- Age, sex and pregnancy. These change body chemistry and breathing.
- Exposure. The same review separates attractiveness from availability: some people simply get more bites because they spend longer outside, unprotected.
A separate review of variability in human attractiveness describes the trait as multifactorial and notes that susceptibility may have a genetic basis, partly through inherited odors, metabolites and skin bacteria. So if your sibling never gets bitten and you always do, genetics may be involved, but through scent chemistry rather than your blood group.
Why “I am always the one who gets bitten” feels true
Part of it is perception. Reactions to bites vary: one person gets a small pink dot, another a hard, swollen welt. If you react strongly, you notice every bite. If your friend barely reacts, they may be bitten just as often and never know. Where you stand matters too. The edge of a group, closest to the water or the brush, takes the first wave.
You cannot change your blood type, but you can change your odds
The practical goal is not to figure out your blood type. It is to cut your exposure. The CDC says to use EPA-registered insect repellents with an active ingredient such as DEET, picaridin, IR3535, oil of lemon eucalyptus, PMD or 2-undecanone, and to look for the EPA registration number on the label. It also recommends loose, long-sleeved shirts and pants, and clothing or gear treated with permethrin.
The CDC also notes that it does not know how well non-EPA-registered repellents work, including some natural ones. We take that seriously, and it shapes how we talk about our own product below.
A few habits help whatever your blood type:
- Apply repellent before you go outside, not after the first bite.
- Cover skin when mosquitoes are most active, which for many species is around dawn and dusk.
- Dump standing water around your campsite or yard, since that is where mosquitoes breed.
- Pick light-colored clothing in loose fits, so there is less contrast and less skin within reach.
- Carry something for the bites that happen anyway.
Our perspective: stop trying to out-think the bite
We hear the blood type question from hikers and parents a lot, usually after a trip where one family member came home with twenty bites and another with none. Our honest view is that it is a fun fact and a poor plan. You cannot act on it, and the research does not hold up well enough to build a plan on.
What you can act on is the two halves of the problem. Before a bite, you use a proven repellent and sensible clothing. After a bite, you want relief that does not add to the irritation. That second half is why we make a balm with five ingredients: beeswax, coconut oil, baking soda, lemongrass oil and wintergreen oil. It is meant to temporarily ease the itch and irritation of bites from mosquitoes and chiggers, and it is not a repellent. We would rather say that plainly than let anyone leave a repellent at home because of us.
We built it for families and people who are outside a lot, so it is designed to be gentle enough for sensitive skin and children, small enough to pocket and packaged to be recyclable. If you want to understand why we keep the formula short, our notes on soothing ingredients for insect bites explain what each one is there to do.
— Matt
Easing the itch when a bite gets through
A bite itches because your body reacts to proteins in mosquito saliva. Scratching breaks the skin and keeps the cycle going. A few basics:
- Wash the area gently with soap and water.
- Try not to scratch, and keep fingernails short, especially for kids.
- Apply a soothing skin protectant to the bite.
- Watch for signs that need a clinician, such as spreading redness, pus, fever or a very large swelling. Talk to your doctor or your child’s pediatrician if any of those show up.
Our Just Bite Me balm is a skin protectant made for exactly this moment: a quick swipe on the bite, then back to your hike or your campfire.
It works well in a daypack or tent pocket, and it also helps with minor skin irritations and stings. If you plan trips with kids, our family outdoor bug bite kit guide shows how to put a small kit together. For camping specifically, see our tips on natural remedies for mosquito bites while camping.
Why a short ingredient list matters outdoors
When you apply something to bitten or scratched skin, you want to know what is in it. A five-ingredient formula is easy to read and easy to check against your family’s sensitivities. If anyone in your group reacts to coconut oil, beeswax or essential oils, skip it and talk to a clinician, as with any skin product. If you are weighing ingredients in general, our overview of harmful chemicals in bug bite products lays out what we look for on labels.
What the blood type question teaches us about mosquito myths
The blood type story is a good example of how a small, preliminary result becomes a “fact.” A lab study finds a difference, a website repeats it, and soon it is everywhere. A few habits keep you from falling for the next one:
- Check the species. A result about malaria mosquitoes in a lab may say little about the ones in your yard.
- Check whether it was replicated. The 2024 review notes a type O result that a follow-up study with similar methods did not confirm.
- Check whether it was retracted. One widely shared type B paper was.
- Be wary of certainty. Words like “clear favorite” usually outrun the data.
FAQ
What blood type attracts mosquitoes the most?
Type O is the one most often named, but the evidence is inconsistent. One 2021 lab study of Aedes aegypti found a significant preference for type B instead. A 2024 review calls the relationship ambiguous and species-dependent.
Are mosquitoes attracted to type O blood?
Sometimes. A 2004 study of Asian tiger mosquitoes found more landings on type O volunteers, but the difference was significant only against type A. Other studies, with other species, did not find the same pattern.
Do mosquitoes bite people with type A blood?
Yes. Type A volunteers drew the fewest landings in the 2004 study, but that does not make them safe. Breath, heat, skin odor and time spent outdoors still decide how many bites you get.
Does blood type make mosquitoes lay more eggs?
The evidence is contradictory. A 2023 review found that a possible preference for type O does not appear to give mosquitoes a reproductive benefit.
What is the best way to avoid bites if I am a mosquito magnet?
Use an EPA-registered repellent, cover your skin and remove standing water nearby. For the bites that still happen, a soothing balm can ease the itch.
Sources
- À la carte: how mosquitoes choose their blood meal (PMC)
- Landing preference of Aedes albopictus (2004)
- Host-seeking behavior and fecundity of the female Aedes (2021)
- Retracted article: Human blood type influences the… (2021)
- Review: Effects of host blood on mosquito reproduction (2023)
- Variability in human attractiveness to mosquitoes (PMC)
- CDC: Preventing Mosquito Bites