INSECTA. 



257 



Order VII. — Hemiptera. 

 In this order there is great variety in the wings, which 

 are often absent, but the mouth parts are typically 

 " sucking," the labium forming a long sucking 'rostrum," 

 and the metamorphosis is incomplete. The Hemiptera 

 are mostly either aquatic insects or dwell on plants and 



Fig. 180. — The Common Louse {Pedicuhts), 



a, Natural size ; b, magnified ; c, a leg ; d^ hair with "nits" or eggs; e, ditto 

 magnified. A degenerate Hemipterous insect. 



Fig. 181. — The Rose Aphis. 



suck their juices. Of the aquatic types the " water- 

 scorpion " has the first pair of legs modified into kind of 

 maxillipedes; the water-boatman swims at the surface on its 

 back, the hind legs imitating a pair of oars. Of the 

 terrestrial type the green aphis is peculiar in reproducing 

 parthenogenetically during the summer, and in secreting a 

 juice of which ants are very fond. 



Order Y III, —Apter a. 

 A few small insects comprise this order, their mouth 

 parts are biting, they have no wings and no metamorphosis. 

 M. 18 



