What blood type do mosquitoes bite most?
If you ask a mosquito, the answer is basically: “whichever of you smells and breathes the most like a meal.” Blood type barely enters into it. The popular belief is that Type O is the mosquito magnet, and there is a sliver of research behind that idea — but it is a much smaller and shakier sliver than the internet suggests.
The most-cited evidence is a 2004 laboratory study by Shirai and colleagues in Japan. Using the Asian tiger mosquito (Aedes albopictus), researchers reported that mosquitoes landed on Type O volunteers about 83% of the time, compared with roughly 46% for Type A, with Type B and AB in between. That is a real, published result. But it involved fewer than 100 people, tested one mosquito species under short controlled conditions, and has not been convincingly reproduced at scale. No large review of mosquito attraction ranks blood type among the strong, reliable drivers.
So the accurate, non-clickbait answer: mosquitoes may land on Type O a little more, but if you are the one being devoured at a GTA backyard barbecue, your blood type is almost never the reason. Read on for what is.
Do mosquitoes like certain blood types at all?
Possibly, but weakly. A couple of studies going back to the 1970s (including work by Wood and colleagues) and the 2004 Shirai study found some ABO patterns. Others found nothing meaningful. When an effect showed up, the pattern usually looked like the table below — but note how small and inconsistent the differences are.
| Blood type | Reported attraction (where any effect was found) | Strength of evidence |
|---|---|---|
| Type O | Landed on most often (~83% in Shirai 2004) | Weak — small samples, rarely reproduced |
| Type B | Intermediate | Very weak |
| Type AB | Intermediate | Very weak |
| Type A | Landed on least often (~46% in Shirai 2004) | Weak — not consistently confirmed |
The key phrase is “where any effect was found.” Plenty of studies find no blood-type effect at all. Treat this table as a curiosity, not a rulebook — there is no blood type that makes you invisible to mosquitoes, and none that guarantees you get eaten.
What the 2004 study actually found — and what it did not
Because the Shirai result is the load-bearing citation behind almost every “mosquitoes love Type O” article online, it is worth stating precisely what the paper reported. It ran in the Journal of Medical Entomology 41(4):796–799 (2004) — the peer-reviewed journal of the Entomological Society of America — and it consisted of 64 human landing tests, not a broad population survey.
Two details usually get stripped out in the retelling, and both cut against the headline:
- The famous 83% / 46% figures are secretor figures. The paper reported roughly 83.3% landings on group O secretors versus about 46.5% on group A secretors. That qualifier matters enormously, and it points straight at the secretor-status explanation in the next section rather than at blood group itself.
- Type O only beat Type A. The difference was meaningful against group A alone — not against group B and not against group AB. The authors further reported that ABH antigens did not, in general, drive landing preference across the ABO groups.
Read that back slowly. The single most-quoted pro-Type-O study contains, inside itself, the strongest available argument that ABO blood group is not really what mosquitoes are responding to.
The two studies everyone else cites: one retracted, one in a journal flagged as predatory
Search this question in the United States or Canada and you will meet the same two citations on page after page after page. Neither is in good standing, and almost nobody who repeats them says so.
The “Type B” paper was retracted in June 2022
A 2021 paper in Scientific Reports — Human blood type influences the host-seeking behavior and fecundity of the Asian malaria vector Anopheles stephensi — reported that mosquitoes preferred group B and laid the most eggs after feeding on it (about 216 eggs on group B, versus roughly 104 on AB and 98 on O). It was retracted on 17 June 2022. Per the retraction notice, figures overlapped with a previously published article, a review of the images and data identified errors and discrepancies that could not be resolved, and the authors lost confidence in the integrity of the data. The authors retracted the paper themselves. Entomology Today, the Entomological Society of America’s news outlet, pulled its write-up of the study and replaced it with a retraction notice.
That withdrawn paper still surfaces high in US search results, and the “some species prefer Type B” line keeps circulating in short-form video off the back of it. Two things are worth knowing before you repeat it: the finding was withdrawn by its own authors, and Anopheles stephensi is an Asian malaria vector that is not established in the United States or Canada in the first place. Even if the result had held, it would have been about a mosquito that does not bite North Americans.
The 2019 “American Journal of Entomology” study is indexed nowhere reputable
The other citation you will see repeated — on blood-bank blogs, pest-control blogs and general-science round-ups alike — is a 2019 paper in the American Journal of Entomology 3(2):43–48, reporting that Aedes aegypti chose the group O feeder most often. The paper is real. But the journal is published by Science Publishing Group, a publisher long and widely flagged as predatory, and it is indexed in neither PubMed/MEDLINE nor the Clarivate Web of Science Master Journal List under either of its ISSNs. It never cleared the quality bar that would let anyone lean on it — which has not stopped half the internet from doing exactly that.
How the three studies actually grade out
| Study | What it claimed | Standing today | Weight it deserves |
|---|---|---|---|
| Shirai et al., 2004 J. Med. Entomol. 41(4) | Group O secretors landed on ~83% vs ~46% for group A secretors; 64 landing tests; Aedes albopictus | Peer-reviewed, indexed, never retracted. Small, single-species, not replicated at scale | Some — the only intact, well-indexed study in the set |
| “American Journal of Entomology,” 2019 | Group O fed on most often; Aedes aegypti | Published by Science Publishing Group, widely flagged as predatory. Not in PubMed/MEDLINE or Web of Science | Very little — unverified by any indexing body |
| Scientific Reports, 2021 | Group B most attractive and highest fecundity; Anopheles stephensi | RETRACTED 17 June 2022 — unresolvable figure and data discrepancies; authors lost confidence in the data | None — withdrawn from the record |
That is the honest state of the evidence, and it is why this page will not tell you your blood type decides anything. One usable study, one unusable one, and one that no longer exists.
Why would Type O blood attract mosquitoes more?
Here is the twist most articles skip: mosquitoes cannot read your blood type. They have no way to sense the ABO antigens sitting on your red blood cells until after they have already bitten you. So if there is any real Type O effect, it must come from something a mosquito can actually detect from the outside — your skin.
That points to secretor status. About 80% of people are “secretors,” meaning they release chemical markers of their blood-group antigens through saliva, sweat, and the surface of their skin. Mosquitoes may pick up on these secreted compounds. Because being a secretor and being Type O often get studied together without separating them, it is genuinely hard to tell whether any signal comes from the O antigen itself or simply from being a secretor. In other words, the “Type O” story may really be a “secretor” story wearing a costume.
One study found that secretors were bitten more than non-secretors regardless of blood type — which suggests the chemical layer on your skin matters more than the letter of your blood group. It is the scent, not the blood.
What blood type do mosquitoes hate or bite the least?
In the studies that found any pattern, Type A tended to be landed on least. But do not go feeling smug (or doomed) about your blood group. The differences were small, the studies were few, and no ABO type actually repels mosquitoes. There is no such thing as mosquito-proof blood.
If you are the person at the campfire who never gets bitten while everyone else swats, the likely reasons have nothing to do with blood type: you may exhale less CO2, run a cooler skin temperature, or simply host a different mix of skin bacteria that mosquitoes find less appealing. Those are the levers that matter.
What blood type do mosquitoes avoid?
None. No ABO group repels mosquitoes or makes you invisible to them. In the few studies that found any pattern at all, Type A was landed on least often — but the gap was small, inconsistent and never reproduced at scale. Type A people still get bitten, and plenty of them get bitten a lot.
It is worth being precise about what “avoid” would even mean. A mosquito decides whether to approach you long before it can sample your blood, using carbon dioxide, heat and skin odour. By the time your ABO antigens are anywhere in the picture, the bite has already happened. So there is no mechanism by which a blood type could cause avoidance, only a mechanism by which secreted skin compounds correlated with blood type might make you marginally less interesting up close.
Does O+ attract mosquitoes?
There is no evidence the “+” part does anything at all. The plus or minus in O+ is the Rh factor, a completely separate antigen system from ABO. Every blood-type study grouped volunteers as A, B, AB and O and did not test Rh, so no research supports O-positive attracting mosquitoes more than O-negative.
The distinction is worth spelling out, because “O+” is how most people actually know their blood type. ABO describes the A and B sugar antigens on the surface of your red blood cells. Rh describes a different protein — principally the D antigen — and it is what makes your type read as positive or negative. They are inherited independently and they do different jobs. A mosquito can detect neither one from the outside. Whatever weak ABO signal the literature picked up, not one study measured Rh, so anyone telling you O-positive blood specifically is a mosquito magnet is inventing the positive part.
Are mosquitoes attracted to the O+ blood group?
Only weakly at best — and part of what looks like an O+ effect is arithmetic rather than biology. O-positive is the most common blood type in the United States, roughly 38% of the population per American Red Cross figures. More O-positive people exist, so more O-positive people report bites. That is a base rate, not a preference.
This is the part of the story almost nobody tells. Gather any ten badly bitten people in an American backyard and you should expect around four of them to be O-positive even if mosquitoes are completely indifferent to blood group, because that is simply how the population is distributed. A poll that asks “mosquito magnets, what is your blood type?” will return “O-positive” as the top answer no matter what the mosquitoes are doing. The myth is partly self-fuelling: the most common blood type will always look like the most-bitten blood type.
Is blood type O+ rare?
No — it is the opposite of rare. O-positive is the most common blood type in the United States at roughly 38% of people, per the American Red Cross, with A-positive next at about 34%. The rarest is AB-negative, at well under 1%. Canada shows a similar distribution, O-positive again first.
| Blood type | Approx. share, United States (American Red Cross) | Approx. share, Canada (Canadian Blood Services) |
|---|---|---|
| O positive | ~38% — most common | ~39% — most common |
| A positive | ~34% | ~36% |
| B positive | ~9% | ~7.6% |
| O negative | ~7% | ~7% |
| A negative | ~6% | ~6% |
| AB positive | ~3% | ~2.5% |
| B negative | ~2% | ~1.4% |
| AB negative | under 1% — rarest | under 1% — rarest |
Set that table beside the “Type O gets bitten most” claim and the base-rate problem becomes obvious. The blood type accused of being a mosquito magnet is also the blood type most people have. Distributions vary by ancestry, so your own community may look different from the national averages above — but in both countries, O-positive leads.
Myth vs fact: blood type and mosquito bites
| The myth | The reality |
|---|---|
| “Mosquitoes love Type O blood.” | One small 2004 study hints at it. It is a weak, unconfirmed trend — not an established fact. |
| “Type A blood repels mosquitoes.” | No blood type repels mosquitoes. Type A was simply landed on slightly less in a couple of studies. |
| “Mosquitoes can sense my blood type.” | They cannot detect ABO antigens before biting. They read your breath, heat, and skin chemistry. |
| “Blood type is why I get bitten so much.” | Almost certainly not. CO2 output, body heat, and skin bacteria explain the vast majority of it. |
| “Nothing I do will change how much I get bitten.” | False. Repellents, clothing, timing, and yard treatment all change how often you get bitten. |
What actually attracts mosquitoes to you (far more than blood type)
Mosquito attraction is a layered process, and blood type is nowhere near the top of the list. Here is roughly how much the real factors matter, from strongest to weakest.
| Factor | How mosquitoes use it | Impact |
|---|---|---|
| Carbon dioxide (CO2) | Detected from your breath up to ~50 m away — the main long-range signal | Very high |
| Skin bacteria & body odour | Microbes produce lactic acid, ammonia & carboxylic acids mosquitoes track close-up | Very high |
| Body heat & moisture | Used at short range to home in on exposed, warm, sweaty skin | High |
| Body size & metabolism | Bigger, more active bodies exhale more CO2 and give off more heat | Moderate |
| Pregnancy | Higher CO2 output and slightly warmer skin | Moderate |
| Exercise & alcohol | Raise CO2, heat, sweat and lactic acid; even one beer measurably increases bites | Moderate |
| Dark clothing | Easier for mosquitoes to see visually against a background | Low–moderate |
| Blood type | Possible weak effect via secreted skin compounds — unproven | Low |
Notice where blood type sits: dead last. For a deeper breakdown of the scent and CO2 story, see our full guide to what attracts mosquitoes to you, and if you suspect you are one of the unlucky 20%, our Am I a mosquito magnet? quiz walks through the real risk factors.
Why am I so prone to mosquito bites?
Because of what you emit, not what you are made of. Roughly one in five people is markedly more attractive to mosquitoes, driven by carbon dioxide output, skin temperature and the specific bacteria living on your skin. Genetics shapes that scent strongly — which is why bite-magnet status runs in families and stays stable year after year.
The best evidence for the genetic half comes from a twin study published in PLOS ONE in 2015 by researchers at the London School of Hygiene & Tropical Medicine. Identical twins, who share their DNA, were far more alike in how attractive they were to mosquitoes than fraternal twins were. The authors estimated that roughly 67% of the variation in attractiveness to mosquitoes is heritable — a similar degree of genetic influence to traits like height. That single number dwarfs anything the entire blood-type literature has produced.
The mechanism sits on your skin, not in your veins. Skin bacteria break sweat down into lactic acid, ammonia and carboxylic acids, and that blend is what a mosquito tracks at close range. A Rockefeller University study published in Cell in 2022 found that people who attract the most mosquitoes carry markedly higher levels of skin carboxylic acids, and that the signature is strikingly stable over years. Mosquito magnets stay mosquito magnets. That persistence is exactly why “I have always been the one who gets eaten alive” is such a common complaint — and it is a skin-chemistry story, not an ABO story.
Do mosquitoes like fat or skinny people?
Body size matters, but not as a judgement about weight. Larger bodies exhale more carbon dioxide and give off more heat and moisture, and those are the signals mosquitoes actually track — so bigger adults get bitten more than small children on average. Height, muscle mass, recent exercise and pregnancy all raise the same signals.
Which means the practical read is about surface area and metabolism rather than body composition. A tall, lean, recently exercising adult puts out plenty of CO2 and heat; so does a pregnant person, whose resting metabolic rate and skin temperature are both slightly elevated. None of this is something to feel judged about, and none of it is something to fix. It is simply a reminder that the levers worth pulling are repellent, clothing, timing and yard treatment — not your body and certainly not your blood group.
Which smell do mosquitoes hate?
The scents with the strongest evidence are the registered repellent actives — DEET, picaridin (called icaridin in Canada), IR3535, and oil of lemon eucalyptus / PMD. Among plant scents, lemon eucalyptus is the only one health agencies list as an actual repellent active. Citronella, peppermint and lavender may deter mosquitoes briefly, but they fade fast.
The distinction that matters is between a smell mosquitoes dislike and a product that reliably keeps them off you for hours. Registered actives are tested for duration of protection; candles and essential-oil sprays are not, and their protective radius in an open backyard is small. For the full evidence rundown on what genuinely repels and what does not, see our guide to smells mosquitoes hate.
What blood type “repels” mosquitoes? (Spoiler: none)
Let’s be blunt: no blood type repels mosquitoes. You cannot change your ABO type — it is set at birth for life — and even if you could, the payoff would be tiny. Anyone selling a “blood-type mosquito hack” is selling a myth.
What genuinely reduces bites for every blood type is straightforward:
- Use a repellent with a PCP registration number containing DEET or icaridin on exposed skin. See our Ontario mosquito repellent guide for what works and for how long.
- Cover up with light-coloured, loose, long sleeves and pants at dawn and dusk when mosquitoes peak.
- Cut the scents that draw them in and lean on the ones they avoid — our roundup of smells mosquitoes hate covers the evidence.
- Kill breeding sites — dump standing water in gutters, planters, and toys every few days so eggs never hatch.
- Treat your yard. A professional barrier spray (from $99 per treatment across the GTA) coats the shaded leaf undersides and shrubs where mosquitoes rest, so treatment reaches them where they spend the day.
Repellent labels in the United States and Canada: picaridin, icaridin, EPA and Health Canada
If you arrived here from a US search, one word above needs translating. “Icaridin” is the Canadian and international name for the ingredient that United States labels call “picaridin.” Same molecule, two names. A shopper in Ohio will not find the word icaridin anywhere on a drugstore shelf, and a shopper in Ontario will not always see picaridin — so scan for either.
The registration mark differs too, and it is the fastest way to tell a real repellent from a novelty. In Canada, a legitimate repellent carries a Health Canada PCP number. In the United States, it carries an EPA registration number (“EPA Reg. No.”) printed on the label, and the EPA runs a public repellent search tool that lets you look up a product and see roughly how long it is expected to work. Either mark means the product went through a regulatory review. A product with neither is not worth putting on your skin.
The US Centers for Disease Control and Prevention (CDC) also lists a wider set of active ingredients than most Canadian articles mention:
| Active ingredient | US label name | Canadian label name | Agency guidance |
|---|---|---|---|
| DEET | DEET | DEET | CDC: suitable from 2 months of age. The longest track record of any active |
| Picaridin / icaridin | Picaridin | Icaridin | Same molecule. CDC: suitable from 2 months of age. Less odour, does not damage plastics the way DEET can |
| IR3535 | IR3535 | Less common on Canadian shelves | CDC: suitable from 2 months of age |
| Oil of lemon eucalyptus (OLE) / PMD | OLE or PMD | p-menthane-3,8-diol (PMD) | CDC: not for children under 3 years. Shorter protection than DEET or picaridin |
| 2-undecanone | 2-undecanone | Rare in Canada | EPA-registered; the newest of the recognised actives |
Three pieces of CDC application guidance that get left out of most articles on this topic:
- Sunscreen first, repellent second. Let the sunscreen absorb, then apply repellent over it — not the other way round, and not a combined product if you can avoid it, since the two need reapplying on different schedules.
- Pregnancy is not a reason to skip repellent. The CDC recommends EPA-registered insect repellents, used as the label directs, including for pregnant and breastfeeding women. Since higher CO2 output makes pregnancy a genuine attraction factor (see the table above), this is the practical answer to it.
- Follow the label on children. DEET, picaridin and IR3535 are appropriate from two months of age; OLE and PMD should not be used on children under three.
As an Amazon Associate I earn from qualifying purchases. BuzzSkito only points to products we would genuinely use or recommend, at no extra cost to you.
If you need to restock before the weekend, a DEET or picaridin spray with a visible EPA registration number (or PCP number in Canada) is the workhorse choice. Check picaridin & DEET repellents on Amazon →
Which mosquito is actually biting you? Species, ranges and biting times
Almost every article on this topic says “mosquitoes” as though there were one of them. There are thousands of species, they behave differently, and — crucially for this page — the blood-type studies only ever tested a couple of them.
| Species | Where it bites people | When it bites | Tested in blood-type research? |
|---|---|---|---|
| Culex pipiens / Cx. quinquefasciatus common house mosquito | Across most of the continental US and southern Canada, Ontario included. The primary West Nile vectors, and vectors of St. Louis encephalitis | Dusk into the night | Never |
| Aedes albopictus Asian tiger mosquito | Southeastern and mid-Atlantic US, cold-tolerant and expanding north; a listed invasive species. CDC publishes estimated potential range maps | Aggressive daytime biter, peaking morning and late afternoon | Yes — Shirai 2004 |
| Aedes aegypti yellow fever mosquito | Southern US — Gulf states, Florida, Texas, Arizona, southern California. Can transmit dengue, Zika and chikungunya | Daytime biter, indoors and out | Yes — the unindexed 2019 paper |
| Anopheles stephensi Asian malaria vector | Asia and the Horn of Africa. Not established in the US or Canada | Night | Yes — in the retracted 2021 paper |
Two consequences fall straight out of that table, and neither appears anywhere else on this topic.
First: nobody has ever tested the mosquito that bites most North Americans. Every blood-type experiment in the literature used Aedes or Anopheles. The dominant biter across most of the United States and all of southern Ontario is Culex — the genus that actually carries West Nile — and it has never been put through a blood-type preference experiment at all. Any confident sentence about “mosquitoes and blood type” is really a sentence about two genera out of thousands of species.
Second: timing advice has to be regional. Dawn and dusk is the right window for Culex, which is why it is the standard line in Ontario and across the northern United States, and it stands. But Aedes aegypti and Aedes albopictus bite hard in broad daylight. If you are in Florida, Texas, Arizona or southern California, treat midday and mid-afternoon as bite time too and wear repellent through the day, not just at the edges of it.
Daytime biting changes what you actually reach for, and this is where a skin repellent stops being the whole answer. Nobody reapplies a spray every few hours across a full working Saturday in the yard, which is why the people dealing with Aedes pressure tend to end up with a zone device on the table instead: a heat-activated repeller warms a treated mat to hold a defined area around where you are sitting, with nothing going on your skin. It needs calm air and the mats are a consumable, so it is a patio-and-picnic-table tool rather than a yard-wide one. Check patio zone repellers on Amazon →
Which country has 0 mosquitos?
Iceland is the answer usually given: it has no established mosquito population, because repeated freeze-thaw cycles kill larvae before they can mature. A handful of individual mosquitoes turning up there recently made international news precisely because it was so unusual. Antarctica is the only continent with none at all.
Everywhere else, the honest answer is that there is no escape by geography. Mosquitoes are established on every other continent, in every US state and in every Canadian province. Which is the whole reason this page ends where it does: you cannot outrun them and you cannot change your blood type, so the levers that remain are repellent, clothing, timing, standing water and the yard itself.
Of the levers on that list, clothing is the one that costs nothing to use again tomorrow. Mosquitoes bite through thin, tight fabric — leggings and a jersey T-shirt are not the barrier people assume — so the cover-up that actually works is loose and light-coloured, and at the far end of it is a mesh bug jacket or a head net for the hour at dusk when the yard is at its worst. It is the cheapest thing in this article that works identically for every blood type, every skin chemistry and every CO2 output. Check bug jackets & head nets on Amazon →
Why this matters in the United States
The Ontario picture below has a US counterpart, and the details differ enough to state separately. West Nile virus is the most common mosquito-borne disease in the continental United States, and the CDC tracks it — along with other arboviruses — through the national ArboNET surveillance system. Most people who are infected never develop symptoms; a small proportion develop serious neurological illness. As in Canada, the way you lower your risk is by lowering your number of bites.
Alongside West Nile, the CDC and state health departments also track:
- Eastern equine encephalitis (EEE) — described by the CDC as rare but serious, occurring in cycles, and reported mainly in eastern and Gulf Coast states.
- Locally acquired dengue — recurring in Florida and Texas, plus an unprecedented cluster of locally acquired cases in Los Angeles County, California. CDC dengue surveillance has logged hundreds of US cases across the current season.
- Northward range expansion of Aedes — CDC publishes estimated potential range maps for Aedes aegypti and Aedes albopictus, and those ranges now reach states that historically had little to think about.
Timing differs as well. In CDC surveillance data, reported cases of mosquito-borne illness in the United States peak in August and September — later in the year than most people assume, and worth knowing if you tend to relax your guard after mid-summer. Season length is regional rather than national:
| Region | Rough mosquito season | Main biting window |
|---|---|---|
| South Florida, south Texas | Effectively year-round | Daytime (Aedes) and dusk (Culex) |
| Gulf Coast & Southeast | Roughly March–November | Daytime and dusk |
| Southwest (AZ, southern CA) | March–November, monsoon-season spike | Daytime and dusk |
| Midwest & Mid-Atlantic | Roughly May–September | Dusk into night |
| Northeast & northern tier | Roughly June–August | Dusk into night |
| Ontario & southern Canada | May–September | Dusk into night |
One last US-specific pointer. Where Canadians get local mosquito guidance from Public Health Ontario and their regional public health unit, Americans have a parallel network that is easy to overlook: land-grant university extension services, which employ extension entomologists in nearly every state. Texas A&M AgriLife Extension, for instance, publishes plain-language mosquito guidance written for Texas conditions, and its extension entomologist Sonja Swiger, Ph.D., has made the point that in any head-to-head comparison something always comes out ahead — which does not make it the winner everywhere, every time. That is precisely the right way to read the blood-type literature. Your state extension service, your county health department and the CDC are the three sources worth checking before any blog on this subject, including this one.
Why this matters in Ontario
Beyond the itch, mosquito bites carry a real if modest health risk in the GTA. Public Health Ontario and the Public Health Agency of Canada (PHAC) track West Nile virus in local mosquito populations every summer, and cases turn up across the province most years, typically peaking in late summer. The virus does not care about your blood type — the way you lower your risk is by lowering your number of bites, full stop.
This is general information, not medical advice. If you develop a fever, severe headache, a spreading rash, or other worrying symptoms after mosquito bites, contact your healthcare provider, and in an emergency call 911.
The bottom line
Could your Type O blood make you a slightly bigger target? Maybe, at the margins — but the science is weak and the effect, if it exists, is dwarfed by things you can actually influence. You cannot change your blood type. You can change how much CO2, heat, and skin-bacteria scent you broadcast, whether you wear repellent, and whether the yard around you is crawling with mosquitoes in the first place. Focus your energy there, and blood type becomes a footnote.
The last item in that sentence — whether the yard around you is producing mosquitoes in the first place — has a DIY half worth doing whatever else you decide. Every mosquito biting you started in standing water within a few hundred metres, and the containers people forget are consistent: the saucer under a planter, a wheelbarrow left out, a clogged gutter, the fold in a pool cover, a rain barrel. Tip what you can tip weekly; for the water that has to stay, a Bti dunk kills the larvae in it before they hatch into anything that can find you. Check the package for the Canadian PCP registration number and follow the label rate. Check Bti mosquito dunks on Amazon →
Related reading
- What Attracts Mosquitoes to You?
- Am I a Mosquito Magnet? (Quiz)
- Smells Mosquitoes Hate
- Ontario Mosquito Repellent Guide 2026
- BuzzSkito Professional Mosquito Control Service
Frequently Asked Questions
What blood type do mosquitoes bite most?+
A small number of studies suggest people with Type O blood are landed on slightly more often than other types, with one lab study (Shirai et al., 2004) reporting Type O drew roughly twice the landings of Type A. But the overall evidence is thin, the studies are small, and the effect has not been reliably reproduced. Blood type is a minor factor at best. Carbon dioxide from your breath, body heat, and the bacteria on your skin drive far more of who gets bitten.
Do mosquitoes really prefer Type O blood?+
There is limited evidence pointing that way, but it is far from settled. The most-cited study is Shirai et al. (2004), where Aedes albopictus mosquitoes landed on Type O volunteers about 83% of the time versus roughly 46% for Type A. The sample was small (fewer than 100 people) and the design was a short controlled test, not real-world backyard conditions. No large, repeated study has confirmed a strong Type O effect, so treat "mosquitoes prefer Type O" as a plausible weak trend rather than a proven fact.
What blood type do mosquitoes hate or bite least?+
In the handful of studies that found any blood-type pattern, Type A tended to be landed on least often, with Type B and AB in between. But the differences were small and inconsistent, and no blood type is actually mosquito-proof. There is no blood type that repels mosquitoes. If you are being bitten less than someone nearby, it is far more likely due to lower CO2 output, cooler skin, or a different skin-bacteria mix than to your ABO group.
Why would Type O blood attract mosquitoes more?+
The honest answer is that scientists are not sure, and the effect may not be real. The leading hypothesis involves "secretor status" rather than blood type itself: about 80% of people secrete chemical markers of their blood-type antigens through skin, sweat, and saliva. Mosquitoes may detect these secreted compounds. Because secretor status and blood type get studied together, it is hard to separate whether any Type O signal comes from the O antigen or simply from being a secretor. It is chemistry on the skin surface, not the blood deep in your veins, that a mosquito can actually sense.
Is being a "secretor" more important than blood type?+
Quite possibly. Roughly 80% of people are secretors, meaning they release blood-group antigens in their bodily fluids and onto their skin. Some research found secretors were bitten more than non-secretors regardless of which ABO type they were. That suggests the chemical layer on your skin matters more than the letter of your blood group. It also helps explain why blood-type studies give messy results: they often do not control for secretor status at all.
What actually attracts mosquitoes more than blood type?+
Carbon dioxide is the number-one long-range cue: mosquitoes detect the CO2 you exhale from up to about 50 metres away. Up close, they use body heat, moisture, and the specific bacteria on your skin, which produce lactic acid, ammonia, and carboxylic acids that mosquitoes find irresistible. Larger bodies, pregnancy, recent exercise, and even one bottle of beer have all been shown to raise your attractiveness. All of these outweigh blood type by a wide margin.
Can I change my blood type to avoid mosquito bites?+
No. Your ABO blood type is fixed for life and cannot be changed, and even if you could change it, the effect on bites would be minor. The practical levers are the things you can actually control: cover exposed skin, use a repellent with DEET or icaridin that carries a PCP registration number, avoid dawn and dusk peaks, reduce standing water where mosquitoes breed, and treat your yard. These reduce bites far more than any blood-type factor ever could.
Do mosquitoes bite some people more than others?+
Yes, consistently. Studies estimate about 20% of people are especially attractive to mosquitoes. This is driven mainly by how much CO2 you exhale (bigger and more active bodies release more), your skin temperature, and your unique skin-microbiome scent. Genetics plays a large role in that scent, which is why bite-magnet tendencies often run in families. Blood type is only a small piece of that picture.
Does Type O blood attract more mosquitoes than Type A?+
In the small 2004 Shirai study it appeared to, with Type O landed on nearly twice as often as Type A. But that single lab result should not be over-read. Larger reviews of mosquito attraction do not list blood type among the strong, reliable drivers. If a Type O person and a Type A person are sitting outside and one gets eaten alive, the difference is almost certainly their CO2, heat, and skin bacteria, not their blood group.
What smells or factors repel mosquitoes regardless of blood type?+
No blood type repels mosquitoes, but several scents and steps do reduce bites for everyone. Repellents with DEET or icaridin that carry a PCP registration number on the label are the most reliable. Some plant compounds like lemon eucalyptus oil (PMD) offer shorter protection. Mosquitoes also tend to avoid certain strong scents, and reducing skin bacteria buildup, wearing light-coloured loose clothing, and eliminating standing water all help far more than worrying about your ABO type.
Does O+ attract mosquitoes?+
There is no evidence the "+" part does anything. The plus or minus in O+ is the Rh factor, a completely separate antigen system from ABO. The blood-type studies grouped volunteers as A, B, AB and O and did not test Rh at all, so no research supports O-positive attracting mosquitoes more than O-negative. Any weak signal in the literature is an ABO signal, and even that is disputed.
Are mosquitoes attracted to the O+ blood group?+
Only weakly at best, and part of what looks like an O+ effect is arithmetic rather than biology. O-positive is the most common blood type in the United States at roughly 38% of the population per American Red Cross figures. More O-positive people exist, so more O-positive people report being bitten. That is a base rate, not a mosquito preference.
Is blood type O+ rare?+
No, it is the opposite of rare. O-positive is the most common blood type in the United States at roughly 38% of people, according to the American Red Cross, followed by A-positive at about 34%. The rarest is AB-negative at well under 1%. Canadian Blood Services reports a similar distribution in Canada, with O-positive again the most common type.
What blood type do mosquitoes avoid?+
None. No ABO group repels mosquitoes or makes you invisible to them. In the few studies that found any pattern at all, Type A was landed on least often, but the gap was small, inconsistent and never reproduced at scale. Type A people still get bitten, and plenty of them get bitten a lot. There is no mosquito-proof blood type.
Why am I so prone to mosquito bites?+
Because of what you emit, not what you are made of. Roughly one in five people is markedly more attractive to mosquitoes, driven by carbon dioxide output, skin temperature and the specific bacteria on your skin. A 2015 PLOS ONE twin study from the London School of Hygiene & Tropical Medicine estimated about 67% of the variation in attractiveness is heritable, which is why bite-magnet status runs in families.
Do mosquitoes like fat or skinny people?+
Body size matters, but not as a judgement about weight. Larger bodies exhale more carbon dioxide and give off more heat and moisture, and those are the signals mosquitoes actually track, so bigger adults get bitten more than small children on average. Height, muscle mass, recent exercise and pregnancy all raise the same signals for the same reason.
Which smell do mosquitoes hate?+
The scents with the best evidence behind them are the registered repellent actives: DEET, picaridin (called icaridin in Canada), IR3535, and oil of lemon eucalyptus or PMD. Among plant scents, lemon eucalyptus is the only one health agencies list as a repellent active ingredient. Citronella, peppermint and lavender may deter mosquitoes briefly but wear off quickly.
Which country has 0 mosquitos?+
Iceland is the answer usually given: it has no established mosquito population, because repeated freeze-thaw cycles kill larvae before they mature. Antarctica is the only continent with none at all. Nowhere else offers an escape. Mosquitoes are established on every other continent, in every US state and in every Canadian province.
Was the study saying mosquitoes prefer Type B blood retracted?+
Yes. The 2021 Scientific Reports paper reporting that Anopheles stephensi preferred blood group B was retracted on 17 June 2022. According to the retraction notice, figures overlapped with a previously published article, a review identified errors and discrepancies that could not be resolved, and the authors lost confidence in the integrity of the data and retracted it themselves. The Type B claim still circulates in videos and articles, but the finding was withdrawn.
Is icaridin the same as picaridin?+
Yes. They are two names for the same repellent ingredient. "Icaridin" is the Canadian and international name and "picaridin" is the name used on United States labels. In Canada look for a Health Canada PCP number on the label; in the United States look for an EPA registration number. Both marks mean the product went through a regulatory review.
Do mosquitoes bite at dawn and dusk or during the day?+
It depends on the species. Culex mosquitoes, the main biters across Ontario and the northern United States and the primary West Nile vectors, bite from dusk into the night. But Aedes aegypti and Aedes albopictus, established across the southern United States and expanding northward, are aggressive daytime biters. In the southern US, midday and mid-afternoon are bite times too.