Only female mosquitoes suck blood

At a distance of tens of meters, mosquitoes can recognize victims (people). They quickly move up to the subject's exposed skin and start sucking blood in a matter of seconds. In contrast, research indicates that female mosquitoes are the true bloodsuckers, while male mosquitoes frequently consume nectar, pollen, tree sap, and fruit juice. Female mosquitoes use the blood they suck to make eggs rather than eating human and animal blood to sustain their bodies. After they have completed sucking blood, they will rest for two to three days so that the body can utilize the iron from the blood to manufacture protein, amino acids, and protein-containing eggs.

It is untrue to state that all mosquitoes bite people. There are mosquito species that do not bite people but mainly feed on the blood of reptiles, birds, and other mammals. Unfortunately, there's no way to tell the difference between male and female mosquitoes as they buzz around your ears, so it's best to just kill as many mosquitoes as possible.