If you’ve had a day where you were surrounded by mosquitoes like a street lamp, you may want to review your clothes. According to an article published in the journal Nature Communications, these pesky bloodsuckers scan their surroundings, pinpointing certain colors like red, orange, black and cyan, after smelling a human breath. Arming yourself with shades of green, purple, blue, and white can help you hide better.
“Imagine being on a sidewalk and smelling pie crust and cinnamon,” said Jeffrey Riffell, a Washington University biologist and author of the study, and continued: “This is probably a sign that there’s an oven nearby, and you can start looking for it. After we sniffed his version, we started learning what visual elements mosquitoes were looking for.”
Riffell and other researchers tested how mosquitoes respond to various hues after being exposed to the carbon dioxide we breathe in each time we exhale. The team first placed female Aedes aegypti mosquitoes, known to transmit dengue, yellow fever, chikungunya, and Zika viruses, in small rooms. The reason why females were chosen for the study is that they are the species that sucks our blood.
Initially, the team watched how the mosquitoes in the cage reacted to stimuli such as colored dots in the absence of odor and saw that they basically did not respond. Next, the researchers repeated the process with some CO2. In this iteration of synthetic human breath, mosquitoes were very interested in red, orange, black, and cyan, but they didn’t care about green, purple, blue, and white.
However, mosquitoes may not be able to distinguish colors as you think. Scientists aren’t sure if insects can “see” color the way we do, just as we can’t “smell CO2.” Still, the colors to avoid have one thing in common: They have longer wavelengths in the visible spectrum.
This brings us to some bad news. Human skin, regardless of pigment, emits long wavelengths similar to red-orange tones. “One of the most common questions asked is, ‘What can I do to prevent mosquitoes from biting me,'” Riffell says. In this study, we found a fourth clue: the color red, which is found not just in your clothes, but in everyone’s skin.”
In fact, Riffell experimented with this part, too, by placing a human hand in a CO2-heavy mosquito cage with and without green gloves. Indeed, the green glove was enough to function as a disguise, leaving the insects indifferent.
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