Mosquitoes mate in the fall, shortly after maturing into adults. Males then die and the females look for shelter. An adult female mosquito survives by hibernating through the winter, thanks to the glycerol in her system acting like antifreeze. Only the female mosquito consumes blood, which she needs to produce eggs. Males live on nectar, which the females eat sometimes also.
Both male and female mosquitoes have antennae, but the male's are much larger and resonate to the sound produced by the female's wings. When mating season arrives, males gather in swarms, sometimes by the thousands! When a female enters the area, she is seized by a male.
Mosquitoes copulate in an involved and unusual way, for insects at least. They do it in the air, stomach pressed against stomach. However, the male's appendage faces the other way, so for mating to take place, the male has to rotate his rear 180 degrees. The male needs 48 hours to twist the organ half circle. In the meantime, he becomes temporarily insensitive to the flutter of the female's wings.
After mating, the female looks for blood.