If you have type O blood and love enjoying a glass or two of beer on an outdoor porch, you may want to keep a lot of bug repellent handy. Scientists have found that mosquitoes find some kinds of blood sweeter than others.
In 1972, British scientists Corinne Wood and Caroline Dore first suggested that the mosquito Anopheles gambiae was especially attracted to type O blood in research published in Nature. Wood and Dore exposed pairs of human volunteers with different blood types to 20 female mosquitoes (males don't suck blood). The mosquitoes, more often than not, zoomed in on the people with type O blood.
A 2004 paper published in the Journal of Medical Entomology by a group of Japanese researchers further examined the tastes. The scientists enlisted 64 people with different blood types who voluntarily exposed themselves to lots of female mosquitoes (thankfully for the study subjects -- but not the bugs -- the mosquitoes had their biting parts removed). People with type O blood were preferred over people with other types. But the real favorites of the bloodsuckers were people who had type O blood and whose skin secreted saccharides – little pieces of sugar.
The Straight Dope puts it succinctly: “if you're a type O secretor, to a mosquito you look like caramel-covered crack.”
Whatever your blood type, it also seems that mosquitoes are attracted to you if you’ve knocked back a few brews. A 2002 study from scientists at the Toyama Medical and Pharmaceutical University in Japan found that even just a 12-ounce cold one can make a person more delicious to mosquitoes. The exact reason why beer sweetens our taste to the bugs is still a mystery. The researchers thought that the amount of alcohol in a person’s sweat or the increase in skin temperature after drinking might be the explanation, but neither measurement proved to be a factor in how often mosquitoes went for a person.
Popular Science has examined the pressing question of whether a mosquito could get drunk by drinking your blood after you’ve pounded a few. While entomologists know that insects can get inebriated, the average mosquito blood meal from a person that’s been drinking contains very little alcohol.
“Before you try to drink a mosquito under the table, heed this warning from Michael Reiskind, an entomologist at Oklahoma State University: The blood alcohol levels required to do so would almost certainly kill you as well,” Bjorn Carey wrote for PopSci in August 2009.
Mosquitoes hone in on people primarily by smelling our breath – specifically, by detecting our exhaled carbon dioxide. The more carbon dioxide one emits, the more attractive you are. That’s why adults are more attractive to the bugs than children, and why pregnant ladies, who exhale more carbon dioxide, should take special care.
You probably have at least one friend who could walk through the most mosquito-infested swamp and come out with nary a single red bump. Some terribly lucky people make their own mosquito repellent. One such skin-derived compound being studied at Rothamsted Research in the U.K. is called 6-methyl-5-hepten-2-one, which smells like “toned-down nail polish remover,” the Wall Street Journal reported in 2009.