Growth (life cycles)

In the full metamorphosis, which is identified with the holometabolia, the stage of youth is called larva and differs considerably from the adult. This difference is the basis of profound modifications, which take place during the nursery stage. The insect suffers a drastic reconstruction of its morphological and anatomical structure, with the exception of the nervous system and the circulatory system. The extent of the changes is such as to require, at this stage, the state of immobility of the insect. The winged sketches are internal and appear only in the pupal stage.
This type of metamorphosis is typical of the most evolved insects, winged or secondarily atteri, such as the beetle. In the most primitive forms of complete metamorphosis, the pupa is mobile. In reality the mobile pupa is an adult in a transition stage, following the last moult. The incomplete metamorphosis, or heterometabolia, is typical of the winged insects, or secondly of the less evolved atteriors, such as the grasshopper. The stage of youth is called neanide and differs from the adult only in its smaller size, the absence of sexual characteristics and, in winged forms, the absence of wings. The transition from the juvenile stage to the adult stage takes place in one or more stages of nymph, during which the appearance of external wing sketches occurs. To the two described above is added a third type, called ametabolia, in which, in reality, there is no metamorphosis. Ametabolia occurs in primitively winged insects (Tisanuri): in this case the juvenile stages have no morphological difference with respect to adults, if not in size, and development takes place without any metamorphosis. This is the case with the dragonfly.