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insect-papilio-3 - larva is completed The eyes antennae...

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Pupation . Mature larvae move to sites on the trunk or stems of the food plant. Here they settle, head uppermost, and spin a pad of silk (1). The caterpillar then moves upwards and clasps the pad with the last pair of prolegs (claspers) while a girdle is spun to support the upper end of the larva when it releases its hold on the stem (2). The body shortens and swells in the thoracic region as blood is pumped forward and air swallowed until the last larval cuticle bursts suddenly behind the head (3). This process, called metamorphosis , takes about 24 hours. Rhythmic contractions of the body and a lubricating moulting fluid allow the split cuticle to pass towards the tail where it is discarded, the pupa attaching itself by the modified last pair of prolegs, the cremaster . At first pale and soft, the pupal cuticle hardens and may be pigmented brown or green to match the background. The pupa does not feed. Reorganization of larval tissue into adult organs, already started in the
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Unformatted text preview: larva, is completed. The eyes, antennae, legs, tongue and forewings of the imago are visible in the pupal cuticle (4). If the pupa is formed at the end of the rains, it may not hatch at once but remain in a dormant state called diapause during which little oxygen is used and normal chemical reactions in the body are replaced by special anaerobic ones, that is, chemical processes not requiring oxygen. Whether pupation lasts for one week or longer, the adult emerges with small, sac-like wings, which are expanded by pumping blood into them. After this they flatten and become chemically hardened. The wings are supported by branching veins, each being hollow and containing a trachea, blood-space and nerve. claspers silk pad silk girdle larval cuticle splitting eye antenna fore-wing accumulating larval cuticle cremaster 1 2 3 4 The pupa Metamorphosis © Dr. N. Jago...
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