Insect biology

The biology of Insects is extremely varied and complex: to so great a number of species there correspond, in fact, as many ways of reproducing and habits of life. Newly hatched individuals are often completely different from what the adults will be: indeed, this stage is reached through the complex mechanism called Metamorphosis. There are various types of metamorphosis, but the two most widespread are complete metamorphosis and incomplete metamorphosis.

The difference between the two types of metamorphosis lies in the pupal stage and the nymphal stage: while the pupa spends a period of quiescence in the form of a chrysalis or inside a cocoon before becoming an imago, the nymph, on the contrary, always remains active, and differs from the adult in its smaller size, in its lack of wings and in its incompletely developed sexual organs. Complete metamorphosis is characteristic of the more highly evolved orders of Insects such as Coleoptera, Lepidoptera and Hymenoptera.

A particular case of Metamorphosis is Parthenogenesis: this takes place when the females of a species lay eggs even without having been fertilised by males. The offspring that hatch from these eggs, consist almost exclusively of female individuals. Among parthenogenetic Insects we may mention the Phasmids, to which the best-known “stick insects” belong.