Wikipedia
Endopterygota, also known as Holometabola, is a superorder of insects within the infraclass Neoptera that go through distinctive larval, pupal, and adult stages. They undergo a radical metamorphosis, with the larval and adult stages differing considerably in their structure and behaviour. This is called holometabolism, or complete metamorphism.
The Endopterygota are among the most diverse insect superorders, with about 850,000 living species divided between 11 orders, containing insects such as butterflies, flies, fleas, bees, ants, and beetles.
They are distinguished from the Exopterygota (or Hemipterodea) by the way in which their wings develop. Endopterygota (meaning literally "internal winged forms") develop wings inside the body and undergo an elaborate metamorphosis involving a pupal stage. Exopterygota ("external winged forms") develop wings on the outside of their bodies and do not go through a pupal stage. The latter trait is plesiomorphic, however, and not exclusively found in the exopterygotes, but also in groups such as Odonata (dragonflies and damselflies), which are not Neoptera, but more basal among insects.
The earliest endopterygote fossils date from the Carboniferous.