150 



ZOOLOGY. 



skin, hardened and horny, becomes for the nymph a solid 

 cocoon, having the appearance of a seed (Fig. 486, a). 



In this division we place, in addition to the flies, properly 

 so called, the gnats, the gad-fly (Fig. 487), the oestrus (Fig. 

 486), &c. 



Pig. 480. Peutatoraa (Cimex ornatus). Fig. 481. Halys, or Wood Bug. 



546. The rhipiptera are insects having also but two 

 wings, but in which the organs are folded longitudinally, like 

 a fan ; two genera only are known, the stylops (Fig. 490) and 

 the xenos, which in their state of larva live as parasites on 

 the abdomen of wasps and other hymenoptera. 



Fig. 482. The Balm Cricket. 



547. The order anoplures or parasites is not numerous, 

 and is composed of insects which are always without wings, 

 which have the mouth arranged for suction, and which do 



