Adult mosquitoes mate in swarms that form 1 meter off ground within days after emerging from pupa stage!

A male will locate of a female of the correct species by listening to the pitch of the female's wings beating.  After mating females will find a host to acquire a blood meal.  After she successfully acquires this meal, she will rest for a few days while digesting the blood.  The protein in the blood is necessary for the development of the eggs.

When the eggs have fully developed, the female will lay the eggs. And the cycle can continue on from there if the female is not univoltine (only lay one set of eggs) but rather, multivoltine (lays multiple sets).  Females over winter as a blood fed nulliparsin in basements and caves, and emerge in early spring to take blood meal and oviposit (lay eggs).