In Periplaneta americana, on an average number of oothecae produced by females are

Options

A. 14-16
B. `11-13`
C. `12-14`
D. `9-10`

Answer

To determine the average number of oothecae produced by female Periplaneta americana (the American cockroach), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Reproductive Anatomy**:
- Female Periplaneta americana has two ovaries.
- Each ovary consists of a group of eight ovarian tubules (also known as ovarioles).

2. **Ova Development**:
- The ovarian tubules contain chains of developing ova (eggs).
- During copulation, the ova descend into the genital chamber.

3. **Fertilization Process**:
- In the genital chamber, the ova are fertilized by sperm.

4. **Formation of Ootheca**:
- Behind the ovaries, there are glands that form a hard egg case known as the ootheca.
- Each ootheca is approximately 8 mm long and dark reddish in color.

5. **Average Production of Oothecae**:
- On average, a female cockroach produces about 9 to 10 oothecae over her lifespan, which can range from 1 to 2 years.
- Each ootheca can contain anywhere from 1 to 16 eggs.

6. **Conclusion**:
- Based on the information gathered, the average number of oothecae produced by female Periplaneta americana is 9 to 10.

### Final Answer:
The average number of oothecae produced by females is **9 to 10**.

---