A new study suggests that whether a mosquito bites you might have a lot to do with the colors that you’re wearing.
The study, conducted by a team of researchers led by University of Washington biologists Diego Alonso San Alberto and Claire Rusch, examined what colors attract mosquitos the most. Using a wind tunnel, they carefully controlled the visual and olfactory environment that mosquitoes were released into and used 3D tracking technology to monitor their movements in the presence of a color dot. The research findings were published in the journal Nature Communications.
The study found that when exposed to carbon dioxide, a gas humans constantly produce via exhalation, yellow fever mosquitoes (Aedes aegypti) developed heightened sensitivity to particular colors like red, orange, black, and cyan — predominantly long-wavelength visual cues. As a result, they flew faster and dwelled longer around those colors. Meanwhile, they remained indifferent to other colors on the spectrum such as green, purple, blue, and white.
The mosquitoes’ attraction to longer wavelength colors makes sense from an evolutionary perspective: Human skin of all shades emanates red-orange light, so it benefits mosquitoes to flock to similar visual stimuli. It also seems reasonable that mosquitoes don’t respond to these same visual signals in the absence of carbon dioxide in their immediate atmosphere; no CO2 means no fresh blood to prey on.
“Imagine you’re on a sidewalk and you smell pie crust and cinnamon,” Jeffrey Riffell, one of the researchers on the team, told Sci-News. “That’s probably a sign that there’s a bakery nearby, and you might start looking around for it.”
The researchers also found that the visual preferences of mosquitoes were genetically coded. Mosquitoes with a mutant copy of a gene that allowed mosquitoes to smell carbon dioxide, along with mosquitoes with a mutant copy of a gene that allowed them to see longer wavelengths of light, expressed muted color preferences.
The scientists repeated the experiment with mosquitoes of other species, and found that the same pattern held: In the presence of CO2, they exhibited special attention to certain colors. However, they found that those colors differed between species. While the orange to red range was a consistent hit across all species, violet, a shorter wavelength, proved to also be eye candy to the mosquito species An. stephensi and Cx. quinquefasciatus.
The study’s results confirm wisdom clothiers have long abided by. In the early 1900s, khaki pants were urged for tropical environments in part because they were unseductive to mosquitoes, and the US military modified its uniform from dark to light blue dress shirts to lessen the attraction of mosquitoes.