Eggs - Depending upon the particular species, the female mosquito lays her eggs either individually or in groups called rafts. Any water-holding area, such as tree holes, ponds, puddles, ditches and artificial containers such as discarded tires and flower pots can serve as a mosquito breeding site. Some mosquitoes (floodwater mosquitoes) lay their eggs in moist substrates without standing water. These eggs are usually resistant to dessication (drying) and hatch when flooded by rainfall, tides, or water diversion to the area. Other species (pool breeders, standing water mosquitoes) lay their eggs only upon standing water and the eggs are not usually resistant to drying. The eggs are placed directly upon the surface of the water or along the edges pools or reservoirs. In either case, water must remain on the surface long enough for the mosquitoes to hatch and complete development.
Larvae - After hatching from the egg, the mosquito larva undergoes a series of growth stages with continuous feeding that eventually will transform the insect from a swimming aquatic form to a flying terrestrial one. Because the larvae are covered in a hard protective skin called the cuticle, they must undergo a series of molts in order to grow. Essentially, the larvae are enclosed in a hard inflexible envelope that is absolutely essential for larval survival, so it can't just be discarded. In order to grow, mosquito larvae grow a new exoskeleton under the old one. This new exoskeleton is soft and flexible at first, thus allowing the larvae to grow. When ready to molt, the larvae then shed the old exoskeleton and the new one hardens when exposed, to protect the larvae's internal organs. Mosquito larvae, also known as "wrigglers" undergo four such molts. The stages between molts are called instars and are numbered from I to IV.
Pupae - After the fourth instar, the development of the future mosquito adult is about to start. The process involves the breakdown of the larval organs and their replacement with the adult ones. During this process, the mosquito takes a new shape; the pupa. The pupa can be considered to be a sealed envelope, where the adult organs are developed from larval tissues. The pupa does not feed or eliminate waste products. Its only contact with the outside is through breathing tubes located on the thorax. After 3 or 4 days, the adult mosquito emerges from the pupa, and after a period of rest, unfold its wings and flies away.
Adults - The male mosquito will usually emerge first, and will linger near the breeding site, waiting for the females. On average, a female mosquito will live 3-6 weeks, but can live up to 5 months. The male's life span is much shorter. Both adult male and female will feed on nectar and plant fluids, but it is only the female that will seek a blood meal, which most species need in order to develop their eggs. Female mosquitoes lay multiple batches of eggs and most species require a blood meal for every batch they lay. Females of some species can develop a limited number of egg batches (usually 1) without taking a blood meal, a quality known as "autogeny". In tropical regions, adult mosquitoes are active throughout the year, but in other areas they become inactive when the temperature drops below 60°F and usually enter hibernation when the seasonal cool temperatures arrive. A few mosquito species hibernate as larvae, usually buried in moist swamp muds, but most overwinter either as eggs laid by the last generation, or as adult, mated females that spend the winter in protected locations such as hollow trees, animal burrows, attics, etc.