30O ZOOLOGY. 



The fleas are to be looked upon as degenerate. They are external 

 parasites without wings. 



Order Lepidoptera (scale-wings). These are Hexapoda which pass 

 through a complete metamorphosis, possess in the adult sucking mouth 

 parts, and have two pairs of large membranous wings covered with scales. 

 The moths and butterflies are the representatives of the order. The larvae 

 are known as caterpillars, which, with a few exceptions, are vegetable 

 feeders. The adult butterfly differs from the moths (typically) in the fact 

 that the former fly by day, hold the wings erect when at rest and have 

 antennae with a club on the end. The butterflies share with the birds the 

 preeminence in beauty among animals. They present many points of 

 interest in their metamorphosis, in their habits, their coloration, their dis- 

 tribution, and their economic effects. 



The caterpillars are usually voracious and may strip their food plant of 

 its leaves and buds. The majority of the larvae have become highly 

 specialized in their food habits, becoming restricted in some instances to 



FIG. 145. 



FIG. 145. The Army Worm (Leucania unipuncta). After Riley. A, caterpillar; 



B, adult moth. 



Questions on the figure. What are the principal facts concerning 

 the habits and economic importance of the army-worm? Why is it so 

 called? 



one species or to a few related species (as illustrated by the tomato worm, 

 which feeds on tomato, potato, and tobacco leaves ; or the cabbage worm 

 which eats the leaves of certain of the cruciferous plants). The distribu- 

 tion of such species is thus clearly determined by that of their host plants. 

 The most injurious to vegetation are the "tent-caterpillars" which occur 

 gregariously and spin a web-like nest; the army-worm, so-called because 

 it appears and moves from its hatching grounds in great numbers; the 

 cotton-boll worm; the canker-worms and fruit-borers. The silk-worm 

 seems to be the only useful member of the order. The clothes-moth lays 

 its eggs in woolens or furs, its larvae thus being exceptional in preferring 

 animal diet. 



The adults are usually short-lived and some do not eat at all. The 

 majority of them suck nectar from flowers and juices from ripe fruits and 

 other objects by means of special tubular mouth parts which are modified 



