(b) : In Musca, development is indirect with complete metamorphosis (holometaboly) including four stages as follows - egg, larva, pupa and adult. In complete metamorphosis, larva after hatching, moults several times to become a fully grown one. It later becomes a pupa within a secreted case, called the puparium. Pupa differentiates into the young adult that breaks the puparium open and emerges outside. Then it grows to a mature form.