Mosquitoes are insects which make up the family Culicidae. They have a pair of scaled wings, a pair of halteres, a slender body, and long legs. The females of most mosquito species suck blood (hematophagy) from other animals, which has made them the most deadly disease vectors known to man, killing millions of people over thousands of years and continuing to kill millions per year by the spread of diseases
Mosquitoes of different species lay their eggs in a variety of water sources that range from small containers to vast expanses of marshland. The larval stage is always aquatic and shuttles from the subsurface where it filter feeds on micro-organisms to the surface to obtain oxygen through a snorkel-like breathing apparatus. The pupal stage does not feed but unlike most Insect pupae is extremely active. The adult emerges from the pupal case using air pressure and assume a terrestrial existence.
The mosquito has four distinct stages in its life cycle: egg, larva, pupa, and adult. The adult is an active flying insect, while the larvae and pupae are aquatic and occur only in water. Depending on the species eggs are laid either on the surface of water or are deposited on moist soil or other objects that will often be flooded. One method of classifying mosquitoes, which is important in the control of the larval stage, is by the type of habitat in which the eggs are laid. Those species that lay eggs singly on the moist soil usually near the edge of temporary pools of water are known as flood water mosquitoes. These eggs only hatch after they have been flooded by water. Psorophora, Aedes, and Ochlerotatus mosquitoes are floodwater mosquitoes which are most abundant shortly after spring rainfall. Those species that lay eggs on the surface of the water, either clumped in rafts or as single floating eggs, are known as permanent water mosquitoes. Anopheles, Culiseta, and Culex are permanent water mosquitoes found in Oklahoma. Floodwater mosquitoes are usually pests in April and May in Oklahoma, with permanent water mosquitoes being problems later in the summer.
Mosquitoes are a vector agent that carries disease-causing viruses and parasites from person to person without catching the disease themselves. Female mosquitoes suck blood from people and other animals as part of their eating and breeding habits. The female mosquito that bites an infected person and then bites an uninfected person might leave traces of virus or parasite from the infected person's blood. The infected blood is injected through, or on, the "dirty" proboscis into the uninfected person's blood and the disease is thus spread from person to person. When a mosquito bites, she also injects saliva and anti-coagulants into the blood which may also contain disease-causing viruses or other parasites. This cycle can be interrupted by killing the mosquitoes, isolating infected people from all mosquitoes while they are infectious or vaccinating the exposed population. All three techniques have been used, often in combination, to control mosquito transmitted diseases. Window screens, introduced in the 1880s, were called "the most humane contribution the 19th century made to the preservation of sanity and good temper.