Which of the following statements is NOT true regarding life cycle of silk worm and production of silk fibres ?

The correct statement that is NOT true is: The pupa develops into caterpillar.

Step-by-step Explanation:

To understand why this statement is incorrect, let us review the stage-by-stage life cycle of a silk moth (Bombyx mori):

1. Egg Stage: The female silk moth lays eggs.
2. Larva / Caterpillar Stage: The eggs hatch into larvae, commonly known as caterpillars or silkworms. During this stage, the caterpillars feed continuously on mulberry leaves and grow in size.
3. Pupa Stage: When the caterpillar is ready to enter the next stage, it weaves a protective net around itself and secretes a protein fiber that hardens upon exposure to air, forming a cocoon. Inside this cocoon, the caterpillar transforms into a pupa.
4. Adult Moth Stage: The pupa further develops inside the cocoon and eventually emerges as an adult silk moth (not a caterpillar).

Evaluating the given options:

• "The larvae of silk moths are called as caterpillars." — True. Silkworm larvae are referred to as caterpillars.
• "The pupa develops into caterpillar." — False / Incorrect statement. The caterpillar develops into a pupa, and the pupa subsequently develops into an adult moth, not back into a caterpillar.
• "Silk fibres are proteins secreted by caterpillars." — True. Silk fibers are mainly made of proteins (fibroin and sericin) secreted by the salivary glands of silkworm caterpillars.
• "The silk yarn is obtained from the cocoon of the silk moth." — True. Cocoon threads are processed and reeled to extract silk yarn.

Therefore, the incorrect statement regarding the life cycle of a silk moth is that the pupa develops into a caterpillar.