XII] WINGS OF INSECTS 247 



(Fig. 101) : in some few cases they have fused together so that the 

 posterior or flying wings are rendered useless. In one great 

 division of the Hemiptera one half of the anterior wing is horny 

 and strongly chitinous, the other and posterior half membranous. 

 In the Cockroach, as we have seen, the anterior wings tend to 



Fm. 100. Pachytylus migratorius. A Grasshopper. Natural size. 



become horny and are of little use in flight (Fig. 97). The posterior 

 wings of the same insect when at rest are folded together something 

 like the leaves of a shut fan and many species in several of the 

 orders fold up their hind wings when not in use. The tucking 

 away of these wings under the small elytra is a complicated affair 

 in some Insects such as the Earwig, where the nippers at the end 



