Which life stage of insects undergoes a process where an old skeleton is shed?

The correct answer is the larval stage of insects, where the process of shedding an old skeleton occurs. This process is known as molting, which is crucial for growth and development in insects. During the larval stage, insects increase in size significantly, and the rigid exoskeleton, which does not expand, must be discarded to allow for this growth.

Larvae may molt multiple times throughout their development, each time shedding their old exoskeleton to allow for an increase in body size. This process is vital, as it enables the insect to progress to their next life stage, eventually leading to metamorphosis.

In contrast, the other life stages listed do not experience molting in the same manner. Eggs are the initial life stage and do not undergo development until they hatch. Nymphs undergo incomplete metamorphosis, but they do not shed a skeleton in the same way larvae do; instead, they may grow through a series of molts, transitioning gradually into adults. The pupa stage represents a transformation phase where the insect is undergoing significant internal changes, but it does not involve the shedding of an exoskeleton like the larval stage.