![]() The adult organs such as antennae, wings and copulatory apparatus develop. ![]() The larval organs such as abdominal pro-legs, anal horn and mouth parts are lost. The pupa lies dormant, but undergoes very important active changes which are referred to as metamorphosis. Within a fortnight the caterpillar larva transforms into a conical brownish creature called the pupa or the chrysalis. The silk thread is secreted at the rate of 150 mm per minute. The irregular surface threads are secreted first and the inner continuous thread later. The outer threads, which are initial filaments of the cocoon, are irregular but the inner ones forming later the actual bed of the pupa, is one long continuous thread about 300 metres in length, wound round in concentric rings by constant motion of the head from one side to the other about 65 times per minute. It is formed of a single long continuous thread. The cocoon is a white or yellow, thick, oval capsule which is slightly narrow in the middle. The cocoon serves a comfortable house for the protection of the caterpillar larva for further development. The cocoon formation takes about 3-4 days. The thread becomes wrapped around the body of the caterpillar larva forming a complete covering or pupal case called the cocoon. The sticky substance turns into a fine, long and solid thread or filament of silk into the air. The full-grown larva now stops feeding and now begins to secrete the clear and sticky fluid of its salivary glands through a narrow pore called the spinneret situated on the hypo pharynx. A pair of long sac-like silk-glands now develops into the lateral side of the body. A full-grown larva is about 8 cm long and becomes transparent and golden light brown in appearance. Thus, normally five instars occur.Īfter each moult, the larva grows rapidly. The stage of the larva between the two successive moulting is called instar. During this period the larva moults four times. The caterpillar moves in a characteristic looping manner. In the beginning chopped young mulberry leaves are given as food but with the advancement of age entire and matured leaves are provided as food. The larva is a voracious eater and strongly gregarious. A series of respiratory spiracles or ostia are present on either lateral side of the abdomen. The eighth segment carries a short dorsal anal horn. Each leg is retractile and more or less cylindrical. These are called pro-legs or pseudo-legs. The third, fourth, fifth, sixth and ninth abdominal segments bear ventrally a pair of un-jointed stumpy appendages each. The abdomen consists of ten segments of which first nine are clearly marked, while the tenth one is indistinct. The tip of each leg has a recurved hook for locomotion and ingestion of leaves. Each of the three thoracic segments bears pair of jointed true legs. The thorax forms a hump and consists of three segments in life cycle of mulberry silkworm late stages. The head bears mandibulate mouth and three pairs of ocelli.Ī distinct hook-like structure, the spinneret, is present for the extrusion of silk from the inner silk-gland. The body of larva is distinguishable into a prominent head, distinctly segmented thorax and an elongated abdomen. ![]() The full-grown larva is about 6.00 to 8.00 cm in length. It has a rough, wrinkled, hairless and yellowish white or greyish worm-like body. The newly hatched larva is about 4 to 6 mm in length. The larva of silkworm moth is called caterpillar larva in life cycle of mulberry silkworm.
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