CHAPTER IX 



THE NERVE-WINGED INSECTS, SCORPION-FLIES, CADDIS-FLIES, 

 MAY-FLIES, STONE-FLIES, AND DRAGON-FLIES 



The earlier naturalists grouped all of the insects having four 

 membranous wings with numerous fine cross veins, or nervures, as 

 they were then called, into the order Xeuroptera, or nerve-winged 

 insects, from neuron (nerve) and/te;w/ (wing). Further study has 



mm^m 





FIG. 113. The adult male dobson-fly and its larva, the hellgramite 



(After Comstock) 



shown that these insects are not so nearly related, and that they 

 should be divided into several distinct orders, to exhibit their true 

 relationship. Few of them have any economic importance, and 



89 



