THE MOXTIILY BULLETIN. 375 



AFTERNOON SESSION. 



Chairman Cook. The first paper to be given this afternoon is 

 entitled "The Grape-leaf Hopper." ))y Prof. H. J. Quayle. of the 

 Universitv of California. 



THE GRAPE-LEAF HOPPER. 



By II. J. Quayle, Berkeley, CaL 

 Introduction. 



The commonest and most widely distributed insect attacking the 

 grape in the United States is the grape-leaf hopper or "vine thrips," as 

 many California vineyardists are inclined to call it. Taking the country 

 over it is no doubt the most serious of all the grape insects. It is true 

 that in this State the phylloxera has done more actual damage, but out- 

 side of California the phylloxera is not a pest in this country, although 

 it is native to the states east of the Rocky Mountains ; but the losses from 

 phylloxera are largely passing away before the advent of resistant vine 

 planting, while the insidious hopper is ever present, and, with the 

 extension of planting in different sections, is increasing rather than 

 diminishing. 



Because of the more or less inconspicuous nature of hopper work, 

 iniless, of course, they are abundant, and the fact that they are present 

 in some numljers every year, many growers are inclined to take hoppers 

 as a matter of course ; an inevitable factor in the business, like adverse 

 weather conditions, something beyond our manipulation and something 

 regularly charged to the general account of profit and loss. It is true 

 that so long as the hoppers are present in small numbers, the injury they 

 do is not important, and in such cases it is not worth while attempting 

 anything in the way of control. But where their numbers are excessive, 

 then the injury they do is considerable and a large toll is exacted from 

 our vinej^ards. 



Distribution. 



Outside of California this insect is most important as a pest in the 

 grape belts of Ohio, Pennsylvania and New York. Here in California 

 it occurs in largest numbers in this great interior section, the San Joa- 

 quin and Sacramento valleys. It also occurs in the Coast valleys, but is 

 seldom injurious there ; and also in Southern California, but south of 

 the Tehachapi it is mo.st serious as a pest in the Imperial Valley. 



Nature of Injury. 



The first indication of injury by the grape-leaf hopper is represented 

 by the pale spots scattered about over the leaf surface. As the feeding 

 continues these pale areas become more abundant and finally the entire 

 leaf is of a pale, silvery color. These leaves later turn brown, become 

 dry and functionless, and at last drop from the vine. This dropping of 

 the leaves, especially in the case of young vines, may begin as early as 



