Question

Which of the following have varying number of nymphal instars between (23-45):

• A. Mayflies
• B. Caddisflies
• C. Syrphid flies
• D. House flies

Hint:

Mayflies are unique in two major developmental aspects:
1. Extremely high number of nymphal instars (23--45).
2. Presence of a winged subimago stage (pre-adult) that molts once more to become a true adult.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The developmental cycle of hemimetabolous insects involves successive nymphal molts.
The number of these instars can vary widely depending on the order.

Step 2: Detailed Explanation:
Mayflies (Order: Ephemeroptera) have an exceptionally high and highly variable number of aquatic nymphal (naiad) instars, often ranging between 23 to 45 molts before reaching the subimago stage.
This high number of molts is influenced by species, water temperature, and food availability.
In contrast, holometabolous insects like caddisflies, syrphid flies, and houseflies have a highly fixed, small number of larval instars (typically 3 to 5).

Step 3: Final Answer:
The insects with 23--45 instars are Mayflies, which corresponds to option (A).