`pə), name for the third stage in the life of an insect insect, invertebrate animal of the class Insecta of the phylum Arthropoda. Like other arthropods, an insect has a hard outer covering, or exoskeleton, a segmented body, and jointed legs. Adult insects typically have wings and are the only flying invertebrates...... Click the link for more information. that undergoes complete metamorphosis, i.e., develops from the egg through the larva and the pupa stages to the adult. A complete metamorphosis is characteristic of members of the orders Coleoptera (beetles), Diptera (flies, mosquitoes, and gnats) and Lepidoptera (moths and butterflies). Before entering the pupa stage the insect is an active larva, usually wormlike in form. The pupa is a resting stage in which the insect is transformed into an adult. It does not feed or increase in size, and typically it is outwardly inactive and covered by a hard integument. Internally, however, a great deal of metabolic activity occurs. Some larval organs are destroyed and some adult organs are initiated during this stage. Other adult organs develop from structures already present in the larva. 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. Cocoons may be made of bits of woody material held together by silk strands, or woven entirely of silk. Some cocoons are formed on or under the ground, some under tree bark; others are suspended from branches or twigs. Some moths form cocoons by wrapping leaves around themselves and gluing them together with silk. Cocoon building occurs in other insects, e.g., wasps; the material and design of the cocoon vary greatly from one group to another. Very few butterflies make cocoons, but the butterfly pupa, called a chrysalis, is usually suspended by a silk thread, and its integument is often sculptured and brightly colored. The chrysalis of the monarch butterfly is soft green with gold spots. A few insects, e.g., the mosquito mosquito , small, long-legged insect of the order Diptera, the true flies. The females of most species have piercing and sucking mouth parts and apparently they must feed at least once upon mammalian blood before their eggs can develop properly.
..... Click the link for more information. , have active pupae. The duration of the pupa stage varies in different insects from a few days to several months. Many insects pass the winter in the pupa stage, and the imago emerges in the spring.
pupa
Inactive, nonfeeding stage in the life of insects that undergo complete metamorphosis. In a protective covering (cocoon or chrysalis), the larva is transformed into an adult. During pupation, a process controlled by hormones, larval structures break down and adult structures form; wings appear for the first time. The adult emerges either by splitting the pupal skin and chewing its way out or by secreting a fluid that softens the cocoon.
pupa
pupa [′pyü·pə]
Pupa
the intermediate stage of development of insects that undergo complete metamorphosis during the process of ontogenesis. The pupa does not eat and usually is immobile. However, intensive restructuring occurs internally as the insect is transformed from a larva into a mature adult, or imago.
Three types are recognized: exarate, obtected, and coarctate pupae. In the exarate pupa, the wings, antennae, and legs are tightly pressed to the body but not attached to it (as in hyme-nopterans, neuropterans, and most beetles). Trichopteran and raphidiopteran exarate pupae move actively. Obtected pupae have a general cover enclosing the legs, antennae, and wings (as in butterflies, lady bugs, and leaf beetles). This type of pupa is less mobile than the exarate. In the coarctate pupa, the last larval skin is not moulted but turns into an urceolate puparium, in which the pupa lies (as in the higher flies and gall midges). The pupation of larvae usually occurs in protected places, such as in the soil or forest litter, under bark, or in wood. Sometimes pupation occurs openly, on tree bark or leaves. Before pupation the larvae often spin cocoons. For some insects with incomplete metamorphosis (for example, the Coccodea), the males go through a pupal stage.
V. A. SVESHNIKOV
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