A pupa is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages thereof being egg, larva, pupa, and imago. The processes of entering and completing the pupal stage are controlled by the insect's hormones, especially juvenile hormone, prothoracicotropic hormone, and ecdysone. The act of becoming a pupa is called pupation, and the act of emerging from the pupal case is called eclosion or emergence.

कोशित या प्यूपा (pupa) कुछ कायान्तरण करने वाले कुछ कीटों के जीवन-चक्र की एक अवस्था का नाम है। यह कायान्तर के दौरान होने वाली चार अवस्थाओं में से एक अवस्था है। इन कीटों के कायान्तरण की चार अवस्थाएं ये हैं - भ्रूण (embryo), डिंभ (larva), प्यूपा तथा पूर्ण कीट या पूर्णक (imago)।