Houseflies carry out complete metamorphosis. They have a short life span of 1 month. A female housefly lays about 100 to 150 eggs in garbage, faeces, etc… The eggs then hatch within 24 hours into larvae, which are white in colour and are called maggots.
After growing and moulting twice,the maggots look for a dry place and transform into pupa (having a pupal case around it). The pupa later transforms into an adult which breaks out of the pupal case and begins life. The adult is called Imago within 2 weeks. The adult is sexually mature and begins to lay eggs to continue the life cycle.
Diagram of life cycle
par Claude Foumtum