INSECTS. HOMOPTERA. 309 



attacked by vast swarms of Aphides, when their leaves curl up, they 

 grow sickly, and their produce is certain to be greatly reduced. One 

 striking instance is presented by the Hop-fly (Aphis Humuli). 



The Cicadellina or Cercopidae, of which the Aphrophora bifasciata, 

 or common Frog-hopper, have the antennae placed between the eyes, 

 and the scutellum visible that is to say, not covered by a process of 

 the prothorax. The ocelli, which are sometimes wanting, are never 

 more than two in number. These little creatures are always furnished 

 with long hind legs, which assist them in performing most extraordi- 

 nary leaps. 



The best-known British species, so very abundant in gardens, is the 

 Cuckoo-spit, or Froth-fly. The names of cuckoo-spit and froth-fly both 

 allude to the peculiar habit of the insect, when in the larva state, of 

 enveloping itself in a kind of frothy secretion, somewhat resembling 

 saliva; and which, indeed, was formerly supposed to be the saliva of 

 the cuckoo, it being found on the young shoots of plants just about the 

 time that the cuckoo is heard in the woods. The frothy secretion is 

 supposed to be intended to preserve the tender body of the insect from 

 the overpowering effects of the sun, as it has been observed to be pro- 

 duced in exact proportion to the heat of the weather. It is not known 

 exactly how the froth is produced. When by any chance it becomes 



Aphrophora spumaria, Cuckoo-spit. Perfect Insect of 



a. The frothy substance. 5. The pupa. the Cuckoo-spit. 



fig. 140. 



condensed, it drops like rain from the trees on which the insect is 

 found. It is only in its larva or infant state that it produces the froth. 

 The larva and the pupa resemble the perfect insect, except that the 

 larva has no wings, and the pupa has very small ones. The perfect 

 insect, however, has both wings and wing-cases ; and it has the power 

 of flying to a considerable distance. Sometimes, indeed, these insects 

 are seen in vast multitudes on the wing. One of the peculiarities of 

 this insect is its power of leaping, which is so great, that, being assisted 

 by its wings, it will sometimes leap a distance of five or six feet ; 

 which is more than two hundred and fifty times its own length, or as 



