If you're type O and feel like mosquitoes hunt you down at every barbecue, you're not imagining it. Science has your back—and so do the mosquitoes.

Research published in the Journal of Medical Entomology found that mosquitoes landed on people with type O blood 83.3% of the time, compared to just 46.5% for type A. That's nearly double the attack rate. Type B and AB fall somewhere in between, but type O is the clear mosquito favorite.

It's Not Just Your Blood Type—It's What You Leak

Here's where it gets weird: about 85% of people are "secretors," meaning they emit chemical signals of their blood type through their skin, sweat, and other bodily fluids. These signals are oligosaccharides—complex sugars that mosquitoes can detect.

Type O secretors release H antigen, a precursor molecule to A and B antigens. When researchers applied these antigens directly to human skin, mosquitoes swarmed the H antigen significantly more than A antigen. If you're a non-secretor (the other 15%), mosquitoes can't read your blood type through your skin—you're basically flying under the radar.

The mosquito preference breakdown:

Type O secretors: mosquito magnets
Type A secretors: less attractive
Non-secretors of any type: harder for mosquitoes to detect
Type B and AB: somewhere in the middle

Blood Type Is Just One Piece of the Puzzle

Before you curse your genetics, know this: blood type explains only part of why mosquitoes prefer certain people. Other factors matter just as much, if not more.

Carbon dioxide output is huge. Larger people and pregnant women exhale more CO2, creating a bigger target. Mosquitoes can detect CO2 from over 100 feet away.

Body heat and sweat also play roles. Lactic acid, uric acid, and ammonia in your sweat act as mosquito attractants. People who've just exercised are basically ringing a dinner bell.

And then there's your skin microbiome—the unique bacterial ecosystem living on your skin. Some bacterial profiles are irresistible to mosquitoes, while others seem to repel them. This might explain why mosquitoes prefer biting certain body parts, like ankles and feet, where bacteria concentrations differ.

Can You Do Anything About It?

You can't change your blood type, but you can manage other factors. Shower after exercising to wash away sweat and lactic acid. Wear light-colored, loose-fitting clothing. Use EPA-registered repellents with DEET, picaridin, or oil of lemon eucalyptus.

And if you're type O? Well, you might just need more bug spray. The mosquitoes have spoken, and they've chosen you.

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