Eggs are laid one at a time and they float on the surface of the water. In the case of Culex and Culiseta species, the eggs are stuck together in rafts of 200 or more. Anopheles and Aedes species do not make egg rafts but lay their eggs separately. Culex, Culiseta, and Anopheles lay their eggs on water while Aedes lay their eggs on damp soil that will be flooded by water. Most eggs hatch into larvae within 48 hours.
Water is a necessary part of their habitat.
Most larvae have siphon tubes for breathing and hang from the water surface. Anopheles larvae do not have a siphon and lay parallel to the water surface to get a supply of oxygen through a breathing opening. The larvae feed on micro-organisms and organic matter in the water. On the fourth molt the larva changes into a pupa. The pupal stage is a resting, non-feeding stage.