Fruit fly life-cycle, computer illustration. The winged adult stage is at top centre. The female lays eggs (upper right) that contain embryos and hatch into larvae. Three sizes (instars) of larvae are shown here (across bottom). Once the fly larva (maggot) has reached a certain size, it forms a pupal stage (left). The adult fly emerges from the pupa. The average cycle lasts between 40 and 50 days depending on temperature.