Why mosquitoes like some humans more than others — and why we should get rid of them

Some humans are tastier than others — to mosquitoes, anyway.

No surprise, say many of us humans, a long-held hunch confirmed by science. Chemical compounds on our skin attract the mosquitoes — and some of us just smell more appetizing than others.

Jeff Riffle, a professor of biology at the University of Washington in Seattle, conducts his research at a massive insectary at the university, where he has been bitten thousands and thousands of times in the name of research.

The mosquitoes, Riffle explained, are fed treated cow’s blood, unless their colonies are crashing, in which case the human researchers reluctantly must offer their own blood. (“This is not ideal at all,” Riffle said by email. “It shows that these mosquitoes are really specialized to feed on us humans.”)

Some humans attract mosquitoes for reasons they can’t control – they have different skin compounds that appeal to the mosquitoes. But there are variables that can be controlled, like clothing color. Mosquitoes apparently find black, orange, and red clothing most attractive, Riffle told Seattle Now. White and green — less so. They are also attracted to humans who run hot — the sweatier, the chattier, the better.

Related: Who likes a hotter climate? Northwest mosquitoes

By understanding what attracts mosquitoes, Riffle and his colleagues can help companies and others develop lures and traps for mosquitoes.

“We’re in the lab trying to understand the cues, the genes and nervous system, and why they are interested in biting us,” he said. “The ultimate goal is to prevent them from biting us.”

Riffle says certain mosquito populations that evolved alongside humans could be eradicated completely. He says there are so many species of mosquitoes, targeting the mosquitoes that do harm to humans and spread disease would not be a huge disruption to the balance of the ecosystem.

There are roughly 3,500 mosquito species, but a tiny fraction of those seek out human blood – and far fewer spread diseases like dengue, malaria, and Zika.

While not all mosquito species bite humans, within the ones that do bite humans, it’s only the females that seek human blood.

“They are little vampires that will suck your blood to provision their eggs for their offspring,” Riffle said. “The boys are just flying around trying to find females.”

To keep mosquitoes away, the chemical DEET works, Riffle said. Although controversial, he said research has shown that it’s safe for children and pregnant women. If that seems off-putting, lemon and eucalyptus essential oils, applied frequently, can also work.

Related: Why are there so few mosquitoes in Seattle?

Riffle buys clothing from REI that contains mosquito repellant in the fabric.

“If we actually eliminate the mosquito species that are transmitting these diseases, it will have no impact on the ecosystem or the ecology of the environment around us,” Riffle said. “The mosquitoes that are among us are the ones that are the problems that we’re trying to avoid and control.”