INSECTS 



247 



objects on which it rests. The principal characteristics of the cicada, and 

 of all bugs, is that the mouth parts are prolonged into a beak with which 

 the animal first makes a hole and then sucks up the juices of the plants on 

 which it lives. 



Life History. — The 17-year cicada lays her eggs in twigs of trees 

 and in doing this causes the death of the twig. The young leave 

 the tree immediately after hatching, burrow under ground, and 

 pass from thirteen to seventeen years there. In the South this 

 period is shortened. They live by sucking the juices from roots. 

 During this stage they somewhat resemble the grub of the beetle 

 (June bug) in" habits and appearance. When they are about to 



s 



Cicada: 1, adult with wings spread, showing abdomen {Ah.), head (//.), thorax {Th.); 

 S, pupal case, showing the split down the back; 3, ventral view, showing beak (fi.), eye, {£.). 



molt into an adult, they climb above ground, cling to the bark of 

 trees, and then crawl out of the skin as adults. 



Economic Importance. — The bugs are among our most de- 

 structive insects. The most familiar examples of our garden pests 

 are the squash bug; the chinch bug, which yearly does damage 

 estimated at $20,000,000 by sucking the juice from the leaves of 

 grain; the scale insects, our greatest fruit tree pests, especially in 

 the orange groves of California; and the plant lice or a])hids. 



Aphids. — The aphids are among the most interesting of the he- 

 miptera. They are familiar to all as the tiny green lice seen swarm- 

 ing on the stems and leaves of the rose and other cultivated plants. 



