mosquito, (family Culicidae), any of approximately 3,500 species of familiar insects in the fly order, Diptera, that are important in public health because of the bloodsucking habits of the females. Mosquitoes are known to transmit serious diseases, including yellow fever, Zika fever, malaria, filariasis, and dengue.

Mosquitoes are common, flying insects that live in most parts of the world. Over 3,700 types of mosquitoes can be found worldwide. Not all mosquitoes bite people or animals. When mosquitoes bite people, the most common reactions to the bite are itching and swelling.

Mosquitoes (or mosquitos) are approximately 3,600 species of small flies comprising the family Culicidae (from the Latin culex meaning " gnat "). The word "mosquito" (formed by mosca and diminutive -ito) is Spanish for "little fly ".

Mosquitoes are small, flying insects. They have six legs and long mouthparts — used to feed on blood and nectar. Only female mosquitoes feed off of blood.