How do mosquitoes find people in dark?

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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 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 contains a receptor to detect carbon dioxide. These receptors also sense skin odor, according to experiments carried out by a group of scientists at University of California. The human body emits nearly 300 types of odors, most of which attract mosquitoes.
In another series of experiments conducted in 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 the tests, the mosquitoes can detect the smell of carbon dioxide as far 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 very 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.
Chemicals emitting odor unattractive to mosquitoes can be used to repel them. There are also chemicals that emits attractive smell which can be used to lure the insects into traps.
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