nother organism with a rapid life cycle is the fruit fly. However, the fruit fly's life cycle involves a process of metamorphosis. During its life cycle, the fruit fly changes from one form to a completely different form. Each of the four distinct life phases is a natural part of the life cycle It changes from egg to larva to pupa to adult. The egg of an adult female is fertilized by a male and then placed "in a nest" (usually in fruit) by the female. The egg soon hatches into a larva which is an immature animal. Soon, the larva enters into the pupa stage by covering itself with a protective case known as a cocoon. During the pupa stage, change takes place. When ready, the fully developed fruit fly comes out of the pupa. The mature adult fruit fly is now ready to reproduce and continue its life cycle.