About how many times does the nymph of the Periplaneta americana undergo moulting before becoming an adult ?

Options

A. 4
B. 2
C. 17
D. 13

Answer

To determine how many times the nymph of the Periplaneta americana (the American cockroach) undergoes moulting before becoming an adult, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Life Cycle of Periplaneta americana**: The life cycle of the American cockroach begins with an egg that hatches into a nymph. The nymph is an immature form that will develop into an adult.

2. **Identify the Nymphal Stages**: In the life cycle of Periplaneta americana, the nymph undergoes several stages of development. Each of these stages is referred to as a nymphal stage.

3. **Count the Nymphal Stages**: It is known that the nymph of Periplaneta americana goes through a total of 13 nymphal stages before it reaches adulthood.

4. **Determine the Number of Moults**: Each nymphal stage is separated by a process called moulting, where the nymph sheds its exoskeleton to grow. Therefore, if there are 13 nymphal stages, the nymph must undergo 13 moults to transition through these stages.

5. **Conclude the Answer**: Hence, the nymph of Periplaneta americana undergoes moulting **13 times** before becoming an adult.

### Final Answer:
The nymph of Periplaneta americana undergoes moulting **13 times** before becoming an adult.