120 NATUKAL HISTORY OF INSECTS. 



a channel, when not in use; the ocelli are usually wanting, 

 the antennae are generally four-jointed, with the terminal joint 

 thicker than the preceding one; the feet are three-jointed. 



Some of these insects subsist on the juices of plants; others 

 are predaceous; while a few, like the Bed-bug, are parasitic. 



The Tingis (Figs. 306 and 307, enlarged) belongs to this 

 Family; it feeds upon the juices of plants. 



Fig. 306. 



J* 



Fig. 309. 



LICE (Pcdiculidse) . These insects are- of a small size and 

 are destitute of wings; the antennae are filiform and five-jointed; 

 the feet are two-jointed, with a large terminal hook; and the 

 mouth parts are retractile. 



These insects, so far as at present determined, all live para- 

 sitical upon man. 



BIRD-LICE (Mallophagidsi) , These insects are of small size 

 and are destitute of wings; the mouth is furnished with jaws; 

 the antennae are from three to five-jointed; the feet are two- 

 jointed, and usually terminate in one or two claws. 



These insects live parasitical upon birds and other animals. 



