cocoon

Pupa of the rose chafer beetle, Cetonia aurata Tumbler (pupa) of a mosquito. Unlike most pupae, tumblers can swim around actively. A pupa (from Latin pupa 'doll'; pl.: pupae) is the life stage of insects from the Holometabola clade undergoing metamorphosis 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 (adult). 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.

The pupae of different groups of insects have different names such as chrysalis for the pupae of butterflies and tumbler for those of the mosquito family. Unlike the fully motile larval and imago stages, the pupal stage of an insect is typically sessile, where the pupa remains anchored to a location until the metamorphosis is completed, and may be enclosed in protective structures such as cocoons, nests or shells.