THE GRAPE LEAF-HOPPER AND ITS CONTROL.* 



F. Z. HARTZELL. 



SUMMARY. 



The grape leaf-hopper is an important pest of the grape and 

 during the past two years it has been on the increase in Chau- 

 tauqua county. In many vineyards the necessity for efficient 

 methods of control has been apparent. The insect weakens the 

 vines by piercing the epidermis of the under side of the leaf and 

 sucking the cell sap, thus injuring the cells and exposing them 

 to the drying action of the air. This injury results in a decrease 

 in the amount of wood, and it also affects the quantity and 

 quality of the fruit. Fruit from badly infested vines is poorly 

 ripened. 



The leaf-hopper is a sucking insect and lives on the under sides 

 of the grape leaves. Eggs are laid during June by the overwin- 

 tering adults, and by the beginning of July the young nymphs 

 are on the vines in abundance. These nymphs pass through five 

 stages or instars before becoming adults. Nymphs of the first 

 brood mature during the latter part of July and early part of 

 August, and during normal seasons many of them lay eggs from 

 which develops a partial second brood. During igii a complete 

 second brood was observed. Young nymphs of the first instar 

 were found as late as October i. Most of these nymphs become 

 adults before the leaves drop from the grape vine. The adults 

 hibernate among rubbish, grass, weeds and fallen leaves. They 

 are active during the warmer days of the hibernating period and 

 feed on various grasses, preferring the leaves of bush fruits dur- 

 ing the spring before returning to the young foliage of the grape 

 vines. 



During the summer the adults are of a yellowish appearance 

 being covered with darker yellow lines. These darker areas 

 turn salmon before the insects leave the vines in the fall and 

 they become dark red when the insects are in their winter 



*A reprint of Bulletin No. 344, February, 1912; for "Popular Edition," 



see p. 815. 



[3671 



