GRAPE INS?:CTS 



413 



nymphs, but tho foliage is weakened so much that it falls an easy 

 prey to the adult hoppers, into which the nymphs soon develop. 

 From August until the grape leaves fall, the adult hoppers 

 swarm over the vines, sucking the life from the leaves and smut- 

 ting or staining the fruit with their excrement. The loss of the 

 foliage prevents the proper ripening of the fruit, which in con- 

 sequence never acquires its ])roper color, flavor or sweetness. 

 The devastated parts 



""mi 



of vineyards are con- 

 spicuous from a dis- 

 tance as brown blots 

 on the landscape dur- 

 ing late summer and 

 autumn. As the 

 leaves are killed, the 

 hoppers migrate to 

 other vineyards 

 where the pasturage 

 is better. They rise 

 from the vines in 

 swarms when dis- 

 turbed, and often 

 cause the pickers an- 

 noyance by getting 

 into their eyes and 

 ears. With the first 

 heavy frosts the adult hoppers leave the vines and seek winter 

 quarters in near-by grass lands or woodlots. 



Means of control. 



As a rule, in the East the only really serious inj ury to the crop 

 is the result of the feeding of the nymphs and adult hoppers 

 in late summer and early fall. If this can be prevented, most 

 of the loss can be avoided. Commercial growers have, there- 

 fore, as a rule concentrated their efforts on killing as large a 



Fig. 361, 



- Grape leaf showing the work of the 

 grape leaf-hopper nymphs. 



