Which stage of an insect does not pass through a pupal stage before maturing into an adult?

The stage of an insect that does not go through a pupal stage before maturing into an adult is the nymph stage. Insects that develop from nymphs typically undergo a process known as incomplete metamorphosis. This means they develop directly into adulthood without the distinct pupal stage that characterizes complete metamorphosis, which includes egg, larva, pupa, and adult stages.

Nymphs are juvenile forms that resemble adults but are not fully developed. They will shed their exoskeleton multiple times (a process known as molting) as they grow, gradually taking on more adult characteristics until they reach maturity.

In contrast, larvae are typically the immature form of insects with complete metamorphosis, and they do pass through a pupal stage. The pupa represents a transformative phase where significant changes occur, leading to the adult form, and the egg is simply the initial stage of life. Hence, the nymph's development process distinguishes it clearly from the lifecycle stages of insects like butterflies or beetles, which include a pupal stage.