A pupa (Latin pupa for doll, plural: pupae or pupas) is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages: embryo, larva, pupa and imago. (For a list of such insects see Holometabolism). The pupae of different groups of insects have different names such as for the pupae of butterflies and tumbler for those of the mosquito family. Pupae may further be enclosed in other structures such as , nests or shells.