CHAP. IX. DESCRIPTION OF THE ORDER OF INSECTS. 55 



Many of them are wingless (as in Fig. 157, 4, and the Apple- 

 tree Aphis, Fig. 158). In one family the Scale-insects the 



Fig. 157. 







females (such as those of the Red Scale, Fig. 159, Ib) are 

 wingless, and the males (see Fig. 159, 1 a) are provided with 

 only two wings. 



Fig. 159. 



V Heteroptera (Plant-bugs, Soldier-bugs, etc.). These insects 

 have the anterior wings thickened at the base, while the outer 



