Do you know that mosquitoes are drawn to specific colors when they view them?

Researchers say mosquitoes are drawn to human skin due to specific colors including red, orange, and black.

According to a new study led by scientists at the University of Washington, they suggest that mosquitoes after detecting a telltale gas that we exhale — fly toward specific colors, including red, orange, black, and cyan.

Conversely, they ignore green, purple, blue, and white.

The researchers believe this helps explain how mosquitoes find hosts, since human skin, regardless of overall pigmentation, emits a strong red-orange ‘signal’ to their eyes.

Senior author Professor; Jeffrey Riffell, of the University of Washington, Seattle, said: “Mosquitoes appear to use odors to help them distinguish what is nearby, like a host to bite.

“When they smell specific compounds, like CO2 from our breath, that scent stimulates the eyes to scan for specific colors and other visual patterns, which are associated with a potential host, and head to them.”

Avoiding the bloodsuckers this spring and summer may hinge on the right choice of attire to cover your skin, say the US team.

The findings in Nature Communications shed light on why mosquitoes attack some individuals – and leave others alone.

Human skin, regardless of overall pigmentation, emits a strong red-orange ‘signal’ to their eyes. The mosquito’s sense of smell, or olfaction, influences how it responds to visual cues. Knowing what lures the hungry pests also opens the door to developing better repellents, traps, and other methods to keep them at bay.

Prof Riffell, a biologist, said: “One of the most common questions I’m asked is ‘What can I do to stop mosquitoes from biting me?’ “I used to say there are three major cues that attract mosquitoes: your breath, your sweat, and the temperature of your skin.

“In this study, we found a fourth cue: the color red, which can not only be found on your clothes but is also found in everyone’s skin.

“The shade of your skin doesn’t matter, we are all giving off a strong red signature.

“Filtering out those attractive colors in our skin, or wearing clothes that avoid those colors, could be another way to prevent a mosquito biting.”

The researchers tracked the behavior of female Aedes aegypti mosquitoes in a test chamber when exposed to visual and scent cues.

Like all mosquito species, only females drink blood. Bites from A. aegypti can transmit dengue, yellow fever, chikungunya, and Zika. Specific odors were sprayed. Patterns such as a colored dot or a tasty human hand were also presented.

Without any fragrance stimulus, the insects largely ignored the mark at the bottom of the chamber, regardless of colour.

After a spritz of CO2, they continued to pay no attention if it was green, blue, or purple. But they headed straight for the dot when it was red, orange, black, or cyan.

Humans can’t smell CO2, which we and other animals exhale with each breath but Mosquitoes can. Previous research has shown it boosts females’ activity, making them explore surrounding space in search of a host.

The latest study revealed after sniffing the gas, their eyes prefer certain wavelengths in the visual spectrum. It is similar to what might happen when humans smell something good.

Prof Riffell said: “Imagine you are on a sidewalk and you smell pie crust and cinnamon.

“That is probably a sign there is a bakery nearby, and you might start looking around for it.

“Here, we started to learn what visual elements that mosquitoes are looking for after smelling their version of a bakery.”

Most humans have ‘true colour’ vision. We see different wavelengths of light as distinct colours.

For example, 650 nanometers shows up as red while 450 wavelengths look blue.

The researchers do not know whether mosquitoes perceive colors the same way. But most of those the preferred – orange, red and black – correspond to longer wavelengths of light.

Human skin also gives off a long-wavelength signal in the red-orange range.

When the trials were repeated with human skin tone pigmentation cards or a researcher’s bare hand, mosquitoes flew again toward the visual stimulus only after CO2 was introduced. If filters removed long-wavelength signals, or a green-colored glove was worn, they did not.

Mosquitoes with a mutation needed to smell CO2 no longer showed a color preference. Another strain of mutant mosquitoes, with a change related to vision, so they could not ‘see’ long wavelengths of light, was more color-blind in the presence of CO2.

Prof Rifell added: “These experiments lay out the first steps mosquitoes use to find hosts.”

More research is needed to determine how other visual and odor cues, such as skin secretions, help mosquitoes target potential hosts at close range.

Other mosquito species may also have different color preferences, based on their preferred host species. But the new findings add a new layer to mosquito control – colour.