Hemimetabolism

Hemimetabolism or hemimetaboly, also called partial metamorphosis and paurometabolism,[1] is the mode of development of certain insects that includes three distinct stages: the egg, nymph, and the adult stage, or imago.

The nymph often has a thin exoskeleton and resembles the adult stage but lacks wings and functional reproductive organs.

[2] The hemimetabolous insects differ from ametabolous taxa in that the one and only adult instar undergoes no further moulting.

Paurometabolism (gradual) refers to insects whose nymphs occupy the same environment as the adults, as in the family Gerridae of Hemiptera.

The hemimetabolous (partial) insects are those whose nymphs, called naiads, occupy aquatic habitats while the adults are terrestrial.