Any of a group of flies in which the female has needlelike mouthparts and sucks blood before laying eggs. The males feed on plant juices. Some mosquitoes carry diseases such as malaria. (Family Culicidae, order Diptera.)

Human odour in general is attractive to mosquitos, as well as the lactic acid in sweat and the heat of the human body at close range. Peoples' varying reactions to mosquito bites depend on their general allergic reaction and not on the degree of the bite; the allergic reaction is caused by the saliva injected from the mosquito's salivary glands to prevent the host's blood from clotting. The mosquito consumes 4 microlitres of blood when it feeds. Natural mosquito repellents include lavender oil, citronella (from lemon grass), thyme, and eucalyptus oils.