LEPIDOPTERA
The adult insect has the body covered with scales and (with the rare exception of the females of a few species) with four wings also covered with scales. Proboscis, when present, coiled, not segmented, adapted for sucking. Metamorphosis complete, i.e. the young which hatches from the egg is quite unlike the adult, and after undergoing several molts transforms into a quiescent pupa which is frequently enclosed in a cocoon from which the adult later emerges. The larvæ are known as caterpillars. Butterflies and moths.
DIPTERA ([page 285])
The adult insect is provided with two, usually transparent, wings, the second pair of wings of other insects being replaced by a pair of halteres or balancers. In a few rare species the wings, or halteres, or both, are wanting. The mouth parts, which are not segmented, are adapted for sucking. The tarsi are five-segmented. Metamorphosis complete. The larvæ, which are never provided with jointed legs, are variously known as maggots, or grubs, or wrigglers. Flies, midges, mosquitoes.
SIPHONAPTERA ([page 316])
Mouth parts adapted for sucking; body naked or with bristles and spines; prothorax well developed; body compressed; tarsi with five segments; wings absent. Metamorphosis complete. The larva is a wormlike creature. Fleas.