Mosquito is a term applied to any fly of the family Culicidae. The female
mosquito has needle-like mouth-parts and sucks blood before laying eggs. Males feed on plant juices. Some mosquitoes carry diseases such as malaria. Human odour in general is attractive to mosquitoes, also lactic acid in sweat and heat at close range. Peoples' varying reactions to mosquito bites depend on the 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 coagulation of the host's blood. Natural mosquito repellents include lavender oil, citronella (from lemongrass), thyme, and eucalyptus oils.
Mosquitoes are remarkable for their quick genetic development, new species develop in around 100 years, as was discovered when mosquitoes became trapped in the London Underground system when it was built, and in 1998 were discovered to have become distinct species developing to feed first on rats and then on humans rather than their usual sheep hosts. Research Mosquito