Chrysalis of Gulf Fritillary Georgetown, South Carolina
A pupa (plural: pupae or pupas) is the life stage of some insects undergoing transformation. The pupal stage only occurs in insects that undergo a complete metamorphosis. It follows the larval stage and precedes adulthood (imago). Pupae are sessile and have a hard protective coating. During the time of pupation, the adult structures of the insect are formed whilst the larval structures are broken down.
There are two ways in which an insect emerges from the pupa. One is the splitting of the pupal skin. When doing so, the insect chews its way through the skin. The other way is when the insect secretes a fluid that softens the cocoon to a degree where the insect can leave the pupa. The whole process of pupation is controlled by the insect's hormones.
The chrysalis of a butterfly and the cocoon of a moth (Lepidoptera) are common examples of pupae. The pupal stage of the butterfly (cocoon) is most commonly recognized. In these cases the caterpillar is transformed into the adult stage of the insect under the protective covering of the cocoon. Cocoons can be found on bushes where they hang from twigs or are hidden in rolled leaves. Some cocoons can be found in underground litter or in burrows. There are insects that spend the entire winter in the pupal stage.
See also: Brood (honeybee)
External links
3D animations of moth pupal development (http://wwwcivm.mc.duke.edu/civmProjects/manduca/manduca.html)
Most butterflypupae are attached to a surface by a Velcro-like arrangement of a silken pad spun by the caterpillar and a set of hooks (cremaster) at the tip of the pupal abdomen.
Mothpupae are usually dark in color and are usually formed in underground cells, loose in the soil, or in a silkencocoon spun by the caterpillar, sometimes suspended from a twig or concealed in the leaf litter.
Insects emerge (eclose) from the pupa by splitting the pupal case, and the whole process of pupation is controlled by the insect'shormones.
The pupa is a resting stage in which the insect is transformed into an adult.
At the end of the pupa stage, the integument is shed and the imago, or adult form, emerges.
Pupae of moths usually have an additional outer covering, called a cocoon, built by the larva (called a caterpillar) just before it enters the pupa stage.
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