Mosquitoes probably like us more than we like them. But have you ever considered the possibility that those little buzzing pests could be playing favorites, opting for some of us more than others?

A basic biological fact we all learned at toms point is that blood type is extremely important when a blood transfusion is needed. Generally speaking, humans have four main blood types: A, B, AB, and O. (We aren’t talking about the negative and positive blood types just yet.) As you probably know, people with O blood type are universal donors and can donate their blood to anyone who so desires.

What do mosquitoes have to do with it?

Apparently, blood banks are not the only ones who court people with blood type O, mosquitoes are quite fond of them as well. In fact, science has known about it since the 1970s but this field of research has never stopped working. In 2004, the Journal of Medical Entomology published an article about the subject and put the whole thing in numbers. Researchers counted the number of times mosquitoes landed on someone with Type O blood as opposed to type A. They found that type O had 83.3% more landings!

How do they know?

It’s not like mosquitoes take a blood sample before they bite. So, how do they know what a person’s blood type is before deciding to feed on it? The answer is simple. Human skin produces chemicals all the time. We don’t usually see or feel them, but mosquitoes definitely sense them in the air. Those chemicals are determined by a person’s blood type, making some blood types more drool-worthy than others.

What else is delicious?

Blood type is not the only thing that appeals to those winged stingers. One thing that makes a difference is what you wear. Mosquitoes are drawn to dark colors and exposed skin. This way, someone in a short-sleeved black t-shirt is a lot more likely to get bitten than someone in a long-sleeved white top. Another thing to make mosquitoes go nuts over your blood is your metabolism. People with a higher metabolical rate produce more carbon dioxide, which mosquitoes love. Mosquitoes are also big fans of perspiration and are more likely to sting a sweaty person.