CHAP. XVI. FAMILIES OF HEMIPTEKA. 



115 



SCALE-INSECTS (Coccidsi). In these insects, which are also 

 called "Bark-lice," the females (Fig. 293, lc,> are wingless, 

 while the males (Fig. 293, la,) are each provided with two 

 more or less transparent wings ; the feet are one-jointed and 

 terminate in a single claw. Some species are oviparous, while 

 others are viviparous. The Lemon-peel Scale (Fig. 293), the 

 Black-Scale (Fig. 294), and the Cottony Cushion-Scale (Fig. 

 295), belong to this Family. [For additional examples see 

 Chapter XX, 011 Scale Insects.] 



JUMPING PLANT-LICE (Psyllidae'). The insects belonging to 

 this Family are of small size, and have four transparent wings ; 

 the feet are two-jointed; the antenna? are nine 'or ten-jointed? 

 the last joint terminating in two short bristles ; the beak 



Fig. 296. 



Fig. 297. 



apparently arises from the breast. These insects possess the 

 power of jumping ; they subsist on the juices of plants, and a 

 few species live in galls. The Pear-tree Psylla (Fig. 296, adult; 

 297, pupse) belongs to this Family. 



LEAF-HOPPERS (Cercopidse). These insects are provided with 

 four wings, the first pair of which are thick and leathery; the 

 Fig. 298. feet are three-jointed ; the ocelli are two 



in number or are entirely wanting ; the 

 antennae are two-jointed. In a few spe- 

 cies the thorax arises in the form of a 

 hump or a horn, or like a high crest ; in 

 others it is produced on each side in the 

 form of a small horn (as in the Buffalo 

 Tree-hopper, Fig. 155). These insects 



