28 



both wild and domesticated, while the book lice are the 

 minute, fragile insects often seen in books and old papers. 

 The insects of this order are characterized by the possession 

 of biting mouth parts in the larval and adult stages of 

 growth, and two pairs of membranous wings, the two pairs 

 being similar in size and shape. The metamorphosis is 

 incomplete. 



Order VI Neuroptera. Nerve-Winged Insects. 



In this order are included the lace-wing flies (Fig. 22) 

 and others similar in appearance. The principal distin- 

 guishing features are the two pairs of membranous wings 



Fig-. 22. Neuroptera. LEC*- wing fly. 

 Enlarged* (Imperial Dept. Aaric.) 



with many nerves or veins, and cross nerves, the conspicuous 

 antennae, the biting mouth parts, in both larval and adult 

 stages, and the complete metamorphosis. 



Order VII. Lepidoptera. The Scale-Winged Insects. 



This order includes the butterflies and moths. (Fig. 23.) 

 The chief characters are the two pairs of membranous wings 

 covered with overlapping scales. The mouth parts in the 

 larvae are formed for biting, while the adults either are not 

 able to feed at all, or have mouth parts adapted to sucking 

 the nectar of flowers or the juice of ripe fruits. The 

 metamorphosis is complete. The name of the order is 

 derived from the two Greek words lepis, a scale, and pteron, 

 a wing. This order includes many pests to agriculture, such 

 as the moth borer of the sugar-cane, the ootton worm, the 

 giant moth borer, the potato moth and cut worms. Nearly 

 all the injury caused by these insects is brought about by 

 the feeding of the larvae. (Fig. 24.) 



