What is the main characteristic of insects that undergo gradual metamorphosis?

Insects that undergo gradual metamorphosis, also known as hemimetabolism, are characterized by their development process, which does not include a distinct larval stage. Instead, these insects progress through a series of life stages, typically from egg to nymph to adult. The nymphs resemble small adults and gradually develop into their mature form through a series of molts, gaining wings and other adult characteristics over time.

This developmental pattern contrasts with complete metamorphosis, in which insects undergo significant transformation involving distinct life stages: egg, larva, pupa, and adult. Additionally, the notion that insects emerge directly as adults implies an absence of previous developmental stages, which is not accurate for those that experience gradual metamorphosis. The incorrect option suggesting that such insects never reach an adult stage is also misleading, as reaching adulthood is indeed the final goal of their metamorphic process.