Biology notes the silkworm topic of zoology.

Biology notes the silkworm topic of zoology.

  

SYSTEMATIC POSITION

                                                          Phylum - Arthropoda

                                                          Class     - Insecta

                                                          Order    - Lepidoptera

                                                          Family   - Bombycidae

                                                          Genus     - Bombyx

                                                          Species    - mori

HABIT AND HABITAT

Silkworm is used for obtaining silk. It feeds on mulberry leaves. Bombyx mori, existed in the wild throughout Asia. B. mori is native to China, but no longer exists because of sericulture. The Bombyx mori is used for obtaining silk. They are popularly known as silkworms or silk moths.

EXTERNAL FEATURES

Adult silkworm is robust ( strong and healthy), creamy white or yellow in color. The body is divided into the usual 3 regions - is small and bears a pair of compound eyes and a pair of branched antennae. Thorax bears 3 pairs of small legs and 2 pairs of large feeble wings. The abdomen of a female is larger due to the great number of eggs it contains.

LIFE CYCLE--

Silkworm is dioecious. Fertilization is internal and its development includes a complicated metamorphosis. Its life cycle includes 4 stages eggs, caterpillar larva, pupa or chrysalis, imago 

1. Eggs- Soon after fertilization each female lays about 300 - 500 eggs in clusters upon the leaves of the mulberry tree. Female covers the eggs with a gelatinous secretion which sticks them to the leaves. After laying the female does not take food and dies.

2.  Caterpillar larva- The larva that hatches from eggs in about 100 days is known as the caterpillar. The larva molt 4 times. After 4 th instar, it eats voraciously. And full-grown caterpillar is formed after 5 th instar with all developing body parts.

3. Pupa or Chrysalis- A Mature caterpillar stops feeding and returns to a corner among the leaves. Its salivary glands now secrete a sticky fluid. The sticky substance turns into a fine long and solid thread of silk. It becomes wrapped around the body of a caterpillar forming a pupal case or cocoon.

4. Imago- After metamorphic changes take place during pupation. The pupa finally metamorphoses into a baby insect or imago.

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