BULLETIN 198. 



THE GRAPE LEAP-HOPPER. 



195 



cast skins, and later in the season these last skins will be about all that 

 will be seen adhering to the leaf. The accompanying picture, Fig. 12 



(and on the cover of this bulletin), photographed by Mr. W. B. Parker, 

 shows one of these cast skins and the adult which emerged from it. 



Habits of Feeding. The young nymph upon hatching from the egg 

 soon finds a suitable -place on the leaf for inserting its beak, and begins 

 to feed on the plant juices. The majority of them remain during the 

 earlier nymphal stages on the same leaf from which they originally 

 emerged, but later there is more or less migration to other leaves on the 

 vine ; but probably 

 a large number re- 

 main throughout 

 their nymphal life 

 on the same leaf. 



Leaves which had 

 contained large 

 numbers of eggs, 

 some of which were 

 hatched and some 

 not, were always 

 seen to be well 

 stocked with nymphs, 

 while other leaves 

 immediately adjoin- 

 ing were free from 

 both eggs and 

 nymphs. Leaves 

 which had already 

 lost most of their 

 green coloring mat- 

 ter were seen to 



have nymphs in abundance, while fresh green leaves near by, offering 

 a better food supply, were observed to be very free from hoppers. Of 

 course, the nymphs can not leap or fly, and so can not make their 

 way from one leaf to another on different shoots unless they happen 

 to be touching, or else crawl down to the base of the shoot and up on 

 the new one. Leaves on the same shoot were observed to have a great 

 difference in the number of hoppers, always being most abundant on 

 the older and paler colored leaves, where the most eggs were to be 

 found. 



Transfer to Other Food Plants. In order to determine whether 

 nymphs would mature if transferred to other food plants than the 



Fig. 12. Adult grape leaf-hopper just emerged. 



