Pupa

A pupa (Latin: pūpa, 'doll'; plural: pūpae) is the life stage of some insects undergoing transformation between immature and mature stages. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, with four life stages: 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.Fruit fly (Drosophila melanogaster) pupaAn emperor gum moth caterpillar spinning its cocoonLuna moth cocoon and pupaAssortment of Luna moth cocoonsLuna moth emerging from pupa within silk cocoonLuna moth pupa removed from cocoonChrysalis of Gulf fritillaryPupation of Inachis ioMonarch butterfly chrysalisSpecimen of an eclosing Dryas iulia butterflyPupae of Japanagromyza inferna, a gall fly, in gall of Centrosema virginianumPupa of cabbage looper A pupa (Latin: pūpa, 'doll'; plural: pūpae) is the life stage of some insects undergoing transformation between immature and mature stages. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, with four life stages: 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 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. Pupae may further be enclosed in other structures such as cocoons, nests, or shells. The pupal stage follows the larval stage and precedes adulthood (imago) in insects with complete metamorphosis. The pupa is a non-feeding, usually sessile stage, or highly active as in mosquitoes. It is during pupation that the adult structures of the insect are formed while the larval structures are broken down. The adult structures grow from imaginal discs. Pupation may last weeks, months, or even years, depending on temperature and the species of insect. For example, pupation lasts eight to fifteen days in monarch butterflies. The pupa may enter dormancy or diapause until the appropriate season to emerge as an adult insect. In temperate climates pupae usually stay dormant during winter, while in the tropics pupae usually do so during the dry season. Insects emerge (eclose) from pupae by splitting the pupal case. Most butterflies emerge in the morning. In mosquitoes the emergence is in the evening or night. In fleas the process is triggered by vibrations that indicate the possible presence of a suitable host. Prior to emergence, the adult inside the pupal exoskeleton is termed pharate. Once the pharate adult has eclosed from the pupa, the empty pupal exoskeleton is called an exuvia; in most hymenopterans (ants, bees and wasps) the exuvia is so thin and membranous that it becomes 'crumpled' as it is shed. In a few taxa of the Lepidoptera, especially Heliconius, pupal mating is an extreme form of reproductive strategy in which the adult male mates with a female pupa about to emerge, or with the newly moulted female; this is accompanied by other actions such as capping of the reproductive system of the female with the sphragis, denying access to other males, or by exuding an anti-aphrodisiac pheromone. Pupae are usually immobile and are largely defenseless. To overcome this, a common strategy is concealed placement. There are some species of Lycaenid butterflies who are protected in their pupal stage by ants. Another means of defense by pupae of other species is the capability of making sounds or vibrations to scare potential predators. A few species use chemical defenses including toxic secretions. The pupae of social hymenopterans are protected by adult members of the hive. Based on the presence or absence of articulated mandibles that are employed in emerging from a cocoon or pupal case, the pupae can be classified in to two types: Based on whether the pupal appendages are free or attached to the body, the pupae can be classified in three types: