The key to avoiding their bites may be in your clothing.
Get ready to find out how a mosquito sees you: These blood-sucking insects use infrared light to find the best place to bite, leaving you itchy and at risk for disease.
Infrared vision of mosquitoes
In a study published this week in NatureA team of biologists has detailed how Aedes aegypti mosquitoes detect infrared radiation and the morphological and biochemical patterns associated with it. “This includes CO2 from our breath, odors, vision, (convection) heat from our skin, and moisture from our bodies,” explained Avinash Chandel, a biologist at the University of California, Santa Barbara and a co-author of the study, in a press release. “However, each of these signals has its limitations.”
Mosquito bites not only cause itching, but can also transmit diseases such as dengue, yellow fever and Zika. The research team set out to find out how these insects find their hosts to feed on their blood.
How Mosquitoes Find Their Victims
Mosquitoes don’t have very good eyesight, so they rely on a combination of senses to locate their victims. They also use these senses to protect themselves from danger. A 2022 study in Scientific reports found that mosquitoes respond to visual and mechanical cues indicating a threat, such as an open hand ready to swat them, while feeding.
Mosquitoes can detect heat emanating from human skin at a distance of about 10 centimeters. Once on the skin, they can directly sense its temperature. According to a new study, mosquitoes can also detect thermal infrared radiation.
The researchers measured how female mosquitoes searched for their hosts in two areas exposed to human odors and carbon dioxide at the same concentrations we exhale. But one of the areas was also exposed to infrared radiation from a source that measured skin temperature, which doubled the mosquitoes’ search activity. With the infrared source active, the mosquitoes’ sensitivity to heat increased to about 70 centimeters.
How to protect yourself from mosquitoes
“A single signal does not stimulate host-seeking activity,” Craig Montell, a UCSB biologist and lead author of the study, said in a statement. “Infrared radiation only matters in the context of other signals, such as elevated CO2 levels and human odor.”
The team suggests that wearing loose clothing may be an effective defence against mosquitoes as it leaves space between the skin and clothing for infrared heat to dissipate, making it difficult for the insects to find their hosts.