170 HOMOPTEEA. 



plant, the juices of vvhicli seem to be specially 

 appropriated to their use. Such are 



The Tree-hoppers (Cicadce), some of them celebrated 

 for their noisy music. The Cicadae pass their lives 

 upon trees or shrubs, upon the sap of which they live. 



The Plant-lice (Aphides) are small homopterous insects. 

 They abound in every garden, living on trees and 

 plants in countless multitudes; indeed, the fecundity of 

 these creatures seems absolutely boundless. It has been 

 calculated that if a male Aphis were to live to see his 

 progeny of the fifth generation gathered around him, he 

 would find himself the great-great-grandfather of nine 



Fig. 130.— lime-tree aphis. 

 ( The lines under the figure show tJie actual site.) 



billions nine hundred and four millions of Aphides ; or, 

 in other words, of a family about fifty times more nume- 

 rous than all the human inhabitants of this globe. With 

 such a fact before us, we leave our readers to judge what 

 might be the result of their undisturbed multiplication. 

 In the course of a few months, even these apparently 

 desj)icable plant-lice would become a plague, as terrible 

 as any mth which the world has been visited. Fortu- 

 nately, even here, the balance between increase and 

 destruction is held with an unwavering hand, so that 

 when we notice the innumerable enemies by which their 

 legions are unremittingly attacked, we are almost led to 



