Although mosquitoes respond to human breath, sweat, and body temperature, they also have dislikes, such as certain smells. A recent study published in the journal “Nature Communications” has found that mosquitoes, after detecting their target through carbon dioxide, will then avoid certain colors in their subsequent actions.
Scientists have known about the complex pathways through which humans attract mosquitoes. Firstly, mosquitoes can sense exhaled carbon dioxide from as far as 10 meters away. Once they detect the carbon dioxide, they start sensing the human odor. When mosquitoes are very close to the human body, they switch to detecting body heat for precise targeting.
However, colors can interfere with mosquitoes in between. Researchers from the University of Washington in the United States tracked the behavior of female Aedes aegypti mosquitoes in response to different visual cues and carbon dioxide. They placed the mosquitoes in a small testing chamber and exposed them to various objects, such as colored dots or human hands.
When observing mosquito behavior, it has been found that mosquitoes first detect the presence of humans by sensing carbon dioxide. They then scan for certain colors and visual patterns that may indicate a food source. When there is no carbon dioxide in the testing chamber, mosquitoes largely ignore colors. However, when researchers sprayed carbon dioxide, the mosquitoes flew towards red, orange, black, or teal-colored dots while disregarding green, light blue, purple, or white dots.
Mosquitoes dislike light and heat because they can easily become dehydrated and die. Therefore, light colors may instinctively represent danger to them, causing them to avoid light-colored objects that reflect heat. Light blue reflects more heat and light, and mosquitoes also tend to avoid white objects.
Even when carbon dioxide is present in the testing chamber, mosquitoes avoid white objects and instead choose their preferred colors. Mosquitoes also ignore purple, which scientists speculate is due to their preference for longer wavelengths, with purple having the shortest wavelength among all colors.
Mosquitoes also dislike green. In one experiment, when a researcher placed their hands directly outside the testing chamber, mosquitoes were attracted to them. However, when the same researcher extended their hand wearing a green glove, the mosquitoes ignored it and flew past. Even when carbon dioxide was used to attract them, mosquitoes showed no interest in the green glove. It appears that mosquitoes genuinely dislike the color green.
Generally, dark colors attract mosquitoes, such as dark blue and black. Darker shades absorb and retain heat, making it easier for mosquitoes to detect human bodies. Additionally, wearing such colors may cause increased sweating, and lactic acid, an important component of human sweat, is one of the ways mosquitoes track humans. Mosquitoes also have a preference for red, as it is easier for them to detect the red wavelength, and the same applies to orange.
Mosquito detection of humans involves multiple factors, including chemical cues like sweat and carbon dioxide, as well as heat and visual cues. Simply changing one’s attire is not enough to avoid mosquitoes. However, if it is necessary to enter an area with many mosquitoes, experts suggest choosing light-colored clothing to minimize the opportunities for mosquitoes to land on you.