Metamorphosis is a biological process by which animals undergo extreme and rapid physical changes during their life cycle. The transformation of a larva into an adult involving sudden and series of continuous changes in the body of an animal is called metamorphosis. Metamorphosis is especially common in insects, and many insects go through four stages of metamorphosis: egg, larva, pupa, and adult. Some examples of animals that undergo metamorphosis include amphibians like frogs and insects like butterflies, beetles, flies, and wasps. During metamorphosis, genes and chemicals called hormones control the process. The larva eats a lot and sheds its outer covering as it grows. To begin the pupa stage, the larva often builds itself a protective covering, such as a cocoon. Inside this covering, the pupa develops wings and adult body parts. It comes out of its covering as an adult.