The New Student's Reference Work/Metamorphosis

Metamorphosis (mĕt′ ȧ-môr′-fō̇-sĭs), change of form in the life of an animal following the embryo-stage.  It may be complete or incomplete; in the former there is change of form and habit, as with toads and frogs; in the latter the newly-hatched young closely resemble the parent, as with grasshoppers, the young differing from adults only in absence of wings.  Owing to metamorphosis species are protected.  While one form may suffer from certain causes, another form survives and carries on the race.  See Larva, Nymph and Pupa.