We humans mostly use our sense of sight to observe the world around us. When we can’t see something, we can know its direction by listening to its sound. However, not all animals use their senses in the same way. Dogs, for example, rely heavily on the sense of smell – being able to detect even slight smells roughly a thousand times better than a human can. For a mosquito, it is thought that sight and smell play the seminal role in the selection of their targets.
As mentioned in another post, mosquitoes use their visual, olfactory, and thermal senses to spot their target. By using sensory cues, the mosquito first has to locate an object that could be a potential target. Once they decide on feeding off a particular thing, they are directed to it using different senses. When they are at about a distance of 50 feet from the object, they can make out its shape and get a definite idea of what it is. The creatures are very visual and can also spot dark-colored clothing like black, blue, or red more easily in comparison to bright-colored ones. People wearing dark clothes often find themselves surrounded by mosquitoes rather than those with lighter clothes.
In a study, it was found that there is a correlation between blood group and the mosquito attacks. Those with blood group O are more favored by the insects, about twice the number of those with type A blood. They do this by sensing the different chemicals released on people’s skin that can attract them. Particular chemicals, like lactic acid, are “tastier” to a mosquito.
Perhaps the most important thing that attracts mosquitoes is the carbon dioxide exhaled by us. They can detect the gas from as far as fifty meters. So, if someone is out of breath or tends to breathe more deeply than someone who is resting or breathes dimly, they exhale larger quantities of carbon dioxide. This can cause clouds of carbon dioxide to gather around them, making them prone to the attraction of mosquitoes. Obese people often exhale more strongly than others, emitting more carbon dioxide, and mosquitoes relish them.
Also, body temperature plays an important role as well and may cause mosquitoes to flock to a person. Mosquitoes use special thermal sensory information to detect heat in the surrounding. They can feel the heat given off by someone from a radius of approximately 20 centimeters. For example, pregnant women are particularly vulnerable to mosquito attacks, due to their fatty frame as well as the additional body heat. People with higher levels of cholesterol also attract mosquitoes.
Mosquitoes are attracted to various other smells as well. No wonder that our bodies, which emit various odors, are so desirable to them. Certain types of acids produced in the body, such as uric acid, are known to attract mosquitoes because they heighten their sense of smell. Other chemicals that draw mosquitoes towards us include lactic acid, acetone, and estradiol. It is also commonly observed that mosquitoes are attracted to people that are sweating. This is also because of certain chemicals released in our sweat. Our body odors are the results of more than 300 chemicals, and it is not easy to find out exactly which one is the most responsible.
There is also the fact that not all mosquitoes are as hostile as others. Mosquitoes with special smell receptors (like IR8a) are generally more easily attracted than others. Some have also come up with the view that it might not be about the attractive smells, but rather about the repelling ones. Those who are bitten less might be producing odor mosquitoes find unattractive, according to that view.