THE CLASSIFICATION OF INSECTS 85 



called the juguni, at the base of eaeli wing, by means of 

 which the two wings of each side are united during flight. 

 In adult caddis-flies the mandibles are obsolete, while the 

 two pairs of maxilla? unite with the labrum to form an 

 imperfect sucking apparatus. The antennae are long and 

 slender with many joints. The larva? are the case-making 

 " caddis worms," which have biting mouth-parts and feed 

 for the most part upon vegetable substances. The perfect 

 insects are often nocturnal in their habits, and make little 

 use of their wings. The order is represented in all parts 

 of the world. 



Order XVI. — Lepidoptera. 



Moths and butterflies may be distinguished from all 

 other insects by the minute, over-lapping scales which 

 cover their wings and bodies. The mouth-parts are modi- 

 fied to form a sucking tube, or proboscis, which has already 

 been described (page 43). The neuration of the wings is 

 mainly longitudinal, but a few cross nervules are usually 

 present. The larva? are always caterpillars, usually with 

 five pairs of prolegs. They have powerful mandibles, and 

 subsist upon the leaves or wood of plants, although a few 

 species feed upon stored goods, or substances of animal 

 origin, such as wool, wax, and feathers. The pupa is 

 often enclosed in a cocoon formed by the larva ; but in 

 the ease of most butterflies no such protection is provided. 

 The popular division of Lepidoptera into "butterflies" 

 and " moths " is misleading, butterflies being more nearly 

 related to the higher moths than these are to the lower. 

 In the three lowest families of moths the two wings of 

 each side are united by a jugum, like those of caddis-flies. 

 In most other moths the hind-wing is provided with a 

 bristle — the frenulum — which hooks into a kind of strap 

 on the underside of the fore-wing. In butterflies, the 



