Flies undergo which type of metamorphosis?

Flies undergo complete metamorphosis, which is characterized by four distinct life stages: egg, larva (or maggot), pupa, and adult. This process allows for significant changes in form and function as the organism progresses through these stages.

In the case of flies, the larval stage is quite different from the adult form, as the larvae typically do not resemble adult flies at all and have a different lifestyle, often focusing on feeding and growth. The pupal stage involves transformation into the adult fly, where it undergoes a process of reorganization of tissues and organs, resulting in a fully formed adult that can reproduce.

This contrasts with gradual or incomplete metamorphosis, where the young resemble miniature adults and undergo a series of molts without a distinct pupal stage, leading to a more gradual transition into adulthood. No metamorphosis would imply a static form throughout the lifecycle, which does not apply to flies either.