Which of the following is NOT one of the stages in gradual metamorphosis?

In the process of gradual metamorphosis, organisms undergo a series of developmental stages that typically include the egg, nymph, and adult stages. The key aspect of gradual metamorphosis is that it involves direct development from the nymph to the adult, with the nymph resembling a smaller version of the adult rather than going through a distinct pupal stage.

The pupa stage is characteristic of complete metamorphosis, where the organism undergoes a significant transformation in a resting state before emerging as an adult. In contrast, organisms that exhibit gradual metamorphosis do not have this pupal stage; instead, the nymphs grow and molt through several instars until they reach maturity as adults.

Understanding the distinction between these types of metamorphosis is essential for applying pest management practices, as it influences strategies for controlling insect populations at different life stages. Recognizing the absence of the pupal stage in gradual metamorphosis helps clarify the life cycle of many insects such as grasshoppers and true bugs, which rely on the egg, nymph, and adult stages.