☞ The Hexapoda have the head, thorax, and abdomen differentiated, and are mostly winged. They have three pairs of mouth organs, viz., mandibles, maxillæ, and the second maxillæ or labial palpi; three pairs of thoracic legs; and abdominal legs, which are present only in some of the lowest forms, and in the larval state of some of the higher ones. Many (the Metabola) undergo a complete metamorphosis, having larvæ (known as maggots, grubs, caterpillars) very unlike the adult, and pass through a quiescent pupa state in which no food is taken; others (the Hemimetabola) have larvæ much like the adult, expert in lacking wings, and an active pupa, in which rudimentary wings appear. See

Insecta

. The Hexapoda are divided into several orders.