the climatic conditions. Two types of eggs are generally found namely diapause type and non-diapause type. The diapause type is laid by silkworms inhabiting the temperate regions, whereas silkworms belonging to subtropical regions like India lay non-diapause type of eggs. The eggs after ten days of incubation hatch into larva called as caterpillar.
The newly hatched caterpillar is Figure . Different types of silkworms Mulberry Eri Muga Tassar Table . Different types of Silkworm Species of silkmoth Silk Producing States Preferred Food (Leaves) Type Of Silk Bombyx mori Karnataka, Andhra Pradesh and Tamil Nadu Mulberry Mulberry Silk Antheraea assamensis Assam, Meghalaya. Nagaland, Arunachala Pradesh and Manipur Champa Muga Silk Antheraea mylitta West Bengal, Bihar and Jharkand Arjun Tassar Silk Attacus ricini Assam, Meghalaya.
Nagaland, Arunachala Pradesh and Manipur Castor Eri Silk XI Std Biology-Zoology Chapter- about mm in length and is pale, yellowish- white in colour. The caterpillars are provided with well developed mandibulate type of mouth-parts adapted to feed easily on the mulberry leaves. After st , nd , rd and th moultings caterpillars get transformed into nd , rd , th and th instars respectively (Figure12. ).
It takes about to days after hatching. The fully grown caterpillar is . cm in length. It develops salivary glands, stops feeding and undergoes pupation.
The caterpillars stop feeding and move towards the corner among the leaves and secretes a sticky fluid through their silk gland. The secreted fluid comes out through spinneret (a narrow pore situated on the hypopharynx) and takes the form of long fine thread of silk which hardens on exposure to air and is wrapped around the body of caterpillar in the form of a covering called as cocoon. It is the white coloured bed of the pupa whose outer threads are irregular while the inner threads are regular. The length of continuous thread secreted by a caterpillar for the formation of cocoon is about - metres which requires days to complete.
The pupal period lasts for to days