The accepted theory explaining the origin of flies during Redi's time was that maggots were spontaneously generated from rotting meat. Adult flies did not lay their eggs which, in turn, hatched into maggots and then metamorphosed into adult flies. A maggot is a larva of an adult fly. Redi conducted experiments which proved that the theory of the spontaneous generation of maggots is incorrect. He proved that adult flies laid their eggs in meat. These eggs hatched into maggots which then, through a process of metamorphosis evolved into adult flies.
