From perfume, to the color of your shirt, right down to the smelliness of your feet, mosquitoes seem to find any reason to sink themselves into human skin.
Scientists say that stinky feet and socks can be added to the list of factors that attract mosquitoes to feed off human blood. One African scientist is now using that bit of research to help fight malaria in Tanzania by creating traps that give off chemically replicated smelly foot odors, hoping to lure the bloodsuckers that carry the disease to their hosts.
"Scientists have known for a long time that mosquitoes smell people; that they do not see us, but instead they smell us," wrote Dr. Fredros Okumu in an email from Tanzania where he heads the research project at the Ifakara Health Institute. "It is the things that we produce in our breath, sweat of skin that [mosquitoes] use as a signal to find us. So if you are wearing socks, these skin-derived chemicals remain on the sock fabric and can still be detected by mosquitoes even after you have removed your socks."
Okumu's project received a $775,000 grant today from the Bill and Melinda Gates Foundation and Grand Challenges Canada to fund the traps and help further development.
But unclean feet and dirty socks aren't the only things that entice a mosquito to go in for the kill. Experts say that Limburger cheese has also been found to be attractive to certain mosquito populations. Ned Walker, a professor in the Department of Microbiology and Molecular Genetics at Michigan State University, studies mosquitoes extensively. Walker said that everything from body build to the type of perfume you wear can be the difference between deterring and attracting the pests.
"There is a variation among attraction to different people … Men tend to be more attractive because they tend to be bigger than women," said Walker, adding that the floral scents given off by deodorants and perfumes also attract some species of mosquitoes to the skin.
However, determining why some people leave a picnic covered in bites while others escape without a battle wound is still up for debate.
"There are some [species] that are attractive to the odors in humans. But what we want to know is why some mosquitoes are attracted to birds and not mammals, to some subsets of humans but not all humans. This is an active area of research," said Walker.
Joe Conlon, technical adviser at the American Mosquito Control Association, said genetics as well as fair skin may also play a role in appealing to mosquitoes, although scientists remain unsure whether the bites are simply more noticeable on people with fair skin.
And while fair skin might be more attractive to the insects, lighter colors of clothing turn them off.
"It's prudent to dress in light-colored clothing. There is a preference by some species to be attracted to darker colors… Wear loose fitting clothing. Mosquitoes can and will bite through tight-fitting clothing," he said.
Conlon said that the only surefire way of preventing mosquitoes from biting is to wear a repellant, to watch what clothes you wear and to get rid of standing water that collects in places like at the bases of flower pots and in the bottom of air conditioning drip pans.
He also cautioned against using any substitutes to DEET repellants like vitamin B, saying that double blind tests have proven these remedies not to work effectively.
"In many cases, people are not fearful enough. With West Nile Virus falling off the radar, people are less concerned. … People need to [know] that they cannot just ruin your picnic, they can ruin your life," said Conlon.