What is the developmental process in insects called when they undergo three stages: egg, nymph, and adult?

The developmental process in insects that includes the stages of egg, nymph, and adult is known as incomplete metamorphosis. In this process, the nymph is a smaller version of the adult and typically goes through several molts before reaching maturity. This type of development allows for a gradual transformation as the insect grows, with nymphs often resembling miniature adults and gradually increasing in size and developing adult features over time.

In contrast, complete metamorphosis involves four stages: egg, larva, pupa, and adult, where the larval stage is distinctly different from the adult stage. Indirect development is not a widely recognized term in entomology, and typically refers to processes that don't fit neatly into the standard metamorphosis categories, while direct development usually describes organisms that hatch from eggs into a juvenile form that resembles the adult without distinct larval or nymphal stages. Thus, the identification of the process involving egg, nymph, and adult as incomplete metamorphosis is accurate and reflects the typical growth pattern of certain insect species.