274 
Hominoxious Arthropods 
the immature insect resembles the adult except that the immature 
form (i. e. nymph) never has wings, the successive instars during 
the process of growth, therefore, are quite similar; and the meta¬ 
morphosis is thus incomplete. To this order belong the true bugs, 
the plant lice, leaf hoppers, frog hoppers, cicadas, etc. 
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 seg¬ 
mented, 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 larvae 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 larva?, 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. 
COLEOPTERA 
Adult with four wings (rarely wanting), the first pair horny or 
leathery, veinless, forming wing covers which meet in a line along 
the middle of the back. Mouth parts of both immature stages and 
adults adapted for biting and chewing. Metamorphosis complete. 
The larvae of many .species are known as grubs. Beetles. 
