A reference to insects having no metamorphosis (no major change in physical form); that is, the Apterygota (being wingless), in which larvae hatch from eggs in a form essentially identical to the adult except for the size and undeveloped genitalia which develop and the size increases at each molting or periodically shedding of part or all of the outer covering of their bodies (hair, skin, or feathers, etc.) which is then replaced with a new growth.