They're actually singing mating songs for each other
Why do mosquitoes buzz in your ears? The short answer: They can't help it. Mosquitoes' wings make that annoying buzz or whining sound whenever they fly. When they circle your head, looking for a place to land and bite, their buzz sounds louder whenever they're close to your ear.
Both male and female mosquitoes buzz, since they both have wings, but you probably won't notice the whine of the males, because they don't want to drink your blood. So they stay away from your ears, eating nectar, while the females come near to annoy you.
Scientists have discovered that the buzz of mosquitoes is more than just a way to annoy you. It's actually important to help them find suitable mates.
Since female mosquitoes are larger, they flap their wings slower, and males know it. They use the distinctive pitch of the females' buzz to recognize them. Louis M. Roth, who studied yellow fever mosquitoes for the U.S. Army during World War II, noticed that males ignored females whenever the females were quietly resting, but whenever the females were flying, and therefore buzzing, the males wanted to mate with them. The males even wanted to mate with recordings of female mosquitoes or tuning forks that vibrated at the same pitch.
Dr. Christopher Johnston of Baltimore, Maryland had already discovered how mosquitoes can hear, almost a hundred years before. He found that they have an organ in their antenna, which was named the Johnston organ after him. It allows them to recognize the buzz of other mosquitoes.
It took other scientists to discover exactly what made the sound. Though you hear the buzz whenever mosquitoes fly, it's not actually caused by the wings beating against the air. There's an organ at the base of the wings which scrapes and makes the sound when the wings move. British entomologists A. E. Shipley and Edwin Wilson published a paper describing it in 1902, which they called "On a Possible Stridulating Organ in the Mosquito." Stridulating means to make noise, and the toothed organ they found made noise as it rubbed against itself, while the wings moved.
By the middle of the 20th Century, scientists had figured out that mosquitoes have special organs to whine or buzz as they fly, that other mosquitoes can hear the noise, and that the buzz of female mosquitoes makes males want to mate with them.
It wasn't until more recently that researchers Gabriella Gibson and Ian Russell discovered that mosquitoes actually change their buzz to "sing" to each other before they mate. They discovered that when males and females flew nearby, they altered the pitch of their buzz to match each other, and if they matched well enough, they mated. Cornell researchers tried the same experiment with mosquitoes which carry the dangerous disease dengue, and found the same thing.
As scientists learn more about why mosquitoes buzz, they may be able to use that knowledge to help keep them from mating. Fewer mosquitoes mean fewer mosquito bites, and fewer diseases being spread. For example, in this article, researcher Lauren Cator suggests that if scientists can make sterile male mosquitoes who "sing" to females just as well as fertile males, the females will choose the sterile males, and won't produce fertile eggs.
There are a few myths about the mosquitoes you hear buzzing near your ears. Some people say that mosquitoes which buzz, don't bite. Well, that's true. As long as they're buzzing, they're flying, so they won't bite you. But as soon as they land, look out!
Does anybody actually enjoy the sound of mosquitoes buzzing? Apparently, teenagers do! With what scientists are learning about mosquitoes, I suppose it's fitting that teenagers are using an electronic sound called a mosquito buzz as their mating "call."
Cornell researchers have found out that mosquitoes not only buzz in your ears, they buzz in each others' "ears" too, as described in the video below.