How do mosquitoes find people in dark?

Mosquitoes are among the most annoying pests for humans. It might be when you are enjoying a summer evening outside when you suddenly find yourself surrounded by mosquitoes buzzing about you. Despite your swatting, they persist and bite you, rewarding you with welts and stinging sensations. If it was only the pain, we could have at least tolerated. But mosquitoes are transmitters of several life-threatening diseases like malaria and dengue fever, which make them dangerous. Millions die from these diseases across the world every year.

Contrary to popular belief, mosquitoes don’t drink blood as a meal. They feed off mainly plant nectar. Only female mosquitoes bite people, and they do that to get the protein needed to develop their fertile eggs. They have an acute ability to spot their targets and attack them.

Like many other insects, mosquitoes are also attracted to the smell of carbon dioxide. They have a group of nerve cells called cpA neurons which contain a receptor to detect carbon dioxide. These receptors also sense skin odor, according to experiments carried out by a group of scientists at the University of California. The human body emits nearly 300 types of odors, most of which attract mosquitoes.

In another series of experiments conducted by the California Institute of Technology, the scientists found out that mosquitoes use a combination of different senses – visual, olfactory (relating to smell) and thermal – to determine their target. The researchers placed mosquitoes in a tunnel filled with carbon dioxide plumes which attracted the insects. They also found that in the presence of carbon dioxide, mosquitoes zeroed in on objects more, especially warm objects.According to the tests, mosquitoes can detect the smell of carbon dioxide from as far away as 50 meters. They follow the smell and from 15 meters they begin to see the human. They have a keen sense of vision and can spot movement. However, they rely on visual cues only after using the olfactory senses which helps them in time management.

Upon reaching close to the person – within a meter – they can sense the body heat and pick up the odors emitted by the body. They waste no time in attacking their target then. Once they have locked onto the target, it is hard to get rid of them short of killing them. Chemicals emitting odors unattractive to mosquitoes can be used to repel them. There are also chemicals that emit attractive smell which can be used to lure the insects into traps.

Long story short; our carbon dioxide exhalations, our odors, and our body heat give us away. This is why mosquito repellents work so well. They evaporate on our skin and block a mosquito’s sense of smell. There are a few smells that mosquitoes are known to hate and avoid, such as the smell of oranges, lemons, and catnip.

Another fun fact, mosquitoes are attracted to dark colors. So, if you wear light colored clothing, you have a higher chance of repelling mosquitoes compared to your darker clothed associates. This can also be tested with larger variants of mosquitoes that are easier to spot. Keep the lights off and you’ll hear them buzzing around. Turn on the lights and they’ll rush towards the shadowy parts of the room.

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• Is it true that only female mosquito bites? What does male mosquito feed on?