U. S. D. A., B. E. Bui. 97, Part I. 



D. F. I. I., March 31, 1911. 



PAPERS ON DECIDUOUS FRUIT INSECTS AND INSECTICIDES 



SPRAYING EXPERIMENTS AGAINST THE GRAPE LEAF- 

 HOPPER IN THE LAKE ERIE VALLEY. 



By Feed Johnson, 

 Agent and Expert. 



INTRODUCTION. 



The grape leafhopper (Typhlocyba comes Say) (fig. 1) is an enemy 

 of grapevines familiar to almost every vineyardist, and doubtless at 

 times it has become so numerous and destructive in his vineyard as 

 to cause him considerable anxiety. Usually, however, in the vine- 

 yards of the Lake Erie Valley, serious dep- 

 redations by this pest are confined to some- 

 what limited areas adjacent to rough lands 

 and woodlots. A few vines at the ends of 

 the rows or a few rows along the outside of 

 vineyards will be injured year after year 

 until the crop yield on these vines is consid- 

 erably reduced. Under these conditions it 

 receives slight attention from the average 

 vineyardist and is regarded as more or less 

 of a negligible quantity. Periodically, how- 

 ever, some as yet unknown conditions seem 

 to favor its multiplication and it spreads 

 over wide areas causing injury amounting 

 to many thousands of dollars. Such a con- 

 dition obtained in the vineyards of Chautau- 

 qua County, in the vicinity of Westfield, 

 N. Y., during the seasons of 1901 and 

 1902, when many hundreds of acres of 



vineyards suffered greatly from the injury wrought by this pest. 

 In 1903 the insect disappeared to a considerable extent and serious 

 injury was again confined to limited areas until the season of 1910. 

 The insect is now manifestly on the increase and during the past 

 season (1910) spread through large blocks of vineyard. In fact, 



l 



Fig. 1.— The grape leafhopper 

 (Typhlocyba comes var. colo- 

 radensis) : Adult. Greatly 

 enlarged. (Original. ) 



