The larvae of silkworm may be attacked by some diseases. These diseases are caused by the attack of various kinds of parasites like virus, bacteria, fungi etc. Pebrin is caused by a type of protozoa. Due to attack of this disease small black spots appear on the body of the larvae which die due to ill nutrition.
(1) To control this disease, the attacked larvae should be removed.
(2) In suitable germ killing solution the eggs should be kept for few minutes and then in pure water.
A short description of the process of collecting silk:
This process is completed in a few steps:
i. After the formation of cocoons, they are to be kept at a certain temperature This will kill the pupae. Otherwise the pupae would come out within a few days by cutting the cocoon and thereby destroy the continuity of the fibers.
ii. Then the cocoons are to be boiled in water for a while. This removes the sticky substances from the cocoon and helps in easy reeling of the fibers from the cocoon.
iii. Silk is collected by reeling the thread of 8 – 10 cocoons. From 7000 cocoons only one kilogram of thread is obtained.
iv. Instead of killing them all. some are preserved for the use as seeds for furture.