Many people recognize this situation: a calm outdoor gathering, a pleasant evening, and when it ends, one person is covered in mosquito bites while everyone else seems untouched. It doesn’t matter whether repellent was applied, long sleeves were worn, or grass was avoided. The conclusion feels unavoidable—mosquitoes clearly have favorites.

This isn’t bad luck or imagination. Science shows that mosquito attraction is driven by biology, body chemistry, and environmental factors, many of which are far more powerful than people realize.

Mosquitoes Don’t Bite Randomly

Only female mosquitoes bite humans, and they do so because they need blood to reproduce. Over time, they’ve evolved an advanced sensory system that helps them locate the most suitable hosts.

The human body constantly releases signals that act like a tracking system for mosquitoes. Some people simply emit stronger or more attractive signals than others.

Carbon Dioxide: The Strongest Signal

One of the most important factors is carbon dioxide (CO₂). Every breath releases CO₂, and mosquitoes are extremely sensitive to it.

People who are taller, have more body mass, or are physically active tend to emit more CO₂, making them easier for mosquitoes to detect. Body heat works alongside CO₂, guiding mosquitoes directly toward their target.

Body Odor and Skin Bacteria

Natural body odor plays a major role. Human skin is home to millions of bacteria that produce specific chemical compounds. This creates a unique scent profile for each person.

For mosquitoes, certain scent combinations are especially appealing. This has nothing to do with cleanliness—it’s a biological trait that makes some people more attractive than others.

Bl00d Type Matters

Research has shown that blood type influences mosquito preference. People with type O blood are bitten more frequently, while those with type A tend to attract fewer mosquitoes.

Some individuals also release chemical markers through their skin that make their blood type easier for mosquitoes to detect.

Sweat, Lactic Acid, and Exercise

Mosquitoes are often more active around people who have been exercising. That’s because sweat and lactic acid, released through the skin, combine with higher body temperature.

This mix creates a powerful attraction, explaining why bites often increase after physical activity.