Title: Larvae
Course: Communicable Diseases Part 1 - Ethiopia (Full)

Larvae

Larvae (pronounced 'lah-vee') is the plural of larva ('lah-vah'); this stage of the life cycle is called the larval stage ('lah-val'). Pupae (pronounced 'pyoo-pee') is the plural of pupa ('pyoo-pah'); this stage of the life cycle is called the pupal stage ('pyoo-pal').

A larva hatches from the egg after one or two days and generally floats parallel under the water surface, since it needs to breathe air. It feeds by taking up food from the water. When disturbed, the larva quickly swims towards the bottom, but it soon needs to return to the surface to breathe. There are four larval stages or instars. The small larva emerging from the egg is called the first instar. After one or two days it sheds its skin and becomes the second instar, followed by the third and fourth instars at further intervals of about two days each. The larva remains in the fourth instar stage for three or four more days before changing into a pupa. The total time spent in the larval stage is generally eight to ten days at normal tropical water temperatures. At lower temperatures, the larval stages take longer to develop.