Mosquitoes are insect vectors responsible for the transmission of parasitic and viral infections to millions of people worldwide, with substantial morbidity and mortality. Infections transmitted by mosquitoes include malaria, yellow fever, chikungunya and other arboviruses. An understanding of mosquito classification, distinguishing features, and the insect life cycle is important for disease surveillance as well as for designing and implementing effective measures for disease control and prevention. (See "Arthropod-borne encephalitides".)
Issues related to the epidemiology, clinical manifestations, diagnosis and management of the infections transmitted by mosquitoes are discussed separately. (See related topics).
Mosquitoes belong to the class Insecta, order Diptera and family Culicidae. The two subfamilies are Anophelinae (which includes the genus Anopheles, the mosquito vector for malaria) and Culicinae (which includes the genera Aedes [Stegomyia], Culex, Mansonia and Haemagogus, the mosquito vectors for arboviruses and some filariases) (table 1) . Each subfamily has hundreds of species within it, although only a few dozen bite humans and therefore are capable of serving as disease vectors.
Planning disease surveillance and control measures requires identification of the mosquito genus or genera in a particular geographic region based upon the distinguishing features of each life cycle stage. The following discussion highlights the characteristic features of the mosquito subfamilies Anophelinae and Culicinae, to facilitate identification of Anopheline malaria vectors from other types of mosquitoes. Techniques for distinguishing the Culicinae genera are beyond the scope of this discussion and require more detailed entomological expertise.
The mosquito progresses through four distinct stages: egg, larva, pupa, and adult . The full life cycle usually takes about 14 days, but the duration varies with temperature and species. Outside of tropical climates, most mosquito species overwinter as eggs, although some overwinter as larvae or adults.