There are approximately 4,000 different species of mosquitoes distributed throughout the world.
Interestingly, this insect goes through a complete metamorphosis in its life cycle with its immature stages always closely associated with water, mainly stagnant water found in ponds, open wells, old cans, etc.
The eggs are laid on the surface of the water in groups, and have pairs of lateral air floats to keep them at the surface. The eggs hatch after a few hours of being laid and a minute worm-like larval stage will emerge. There are four larval stages which will feed voraciously on micro-organisms present in the water or on the surface. The larva obtains oxygen by coming up to the surface, suspended there by surface tension and taking in air through a pair of spiracles at its hind end.
Many articles taken from 'A word with the doctor', by Dr. John Windsor.