All mosquitoes have four stages of development: egg, larva, pupa and adult, and spend their larval and pupal stages in water. Eggs may be laid singly (Anopheles) or in groups or rafts (Culex) on the water surface, or they may be laid singly out of the water on a surface that will subsequently flood (Aedes, Ochlerotatus, Psorophord).
Although larvae and pupae develop in the water, they are not completely aquatic because they breathe atmospheric oxygen, which is obtained in most species by a siphon tube that penetrates the water surface or, in some species, pierces the roots of aquatic plants (Anopheles larvae have no air tube; instead they have a cluster of small plates and lie suspended horizontally just beneath the water surface.) Larvae feed on microorganisms and particles of organic matter, and they shed their skin four times (each of those four developmental periods is called an instar), growing larger after each molting.
Pupae do not feed, but unlike most other insect pupae, are extremely active. Pupae of a number of mosquito species can complete development on a moist surface.
Development times from egg to adult depend on species characteristics as well as on temperature, and can range from four days to more than a month.
Shortly after adults emerge from the pupal case they mate, and the female seeks a blood meal to obtain the protein necessary for the development of her eggs. A few species may produce a first batch of eggs without this first blood meal, but will seek a blood meal to produce second and further batches of eggs.
Adult mosquitoes, both males and females, rely on plant sugar to help meet their metabolic needs. Only female mosquitoes take blood meals as an excellent protein resource for the development of the eggs. In fact, male mouthparts are not suited for piercing skin.