288 Report of the Deya&TKent of Entomology of the 



the vine. The amount of injury to vineyards varies directly with 

 their proximity to favorable hibernating places and spring food 

 plants. 



Spraying experiments during 191 2 showed, (1) that Black 

 Leaf 40, one part to 1600 parts of water or bordeaux mixture, is 

 an efficient spray for the leaf-hopper. (2) The automatic attach- 

 ment is a practical machine in the hands of careful sprayers. 

 (3) The fruit from vines protected from the leaf-hopper is 

 superior to fruit from vines subjected to the attacks of this pest. 

 Chemical analyses of grapes from sprayed vines gave a gain of 

 from 8 to 68 per ct. in sugar over those from untreated vines, 

 while the unsprayed grapes had from o to 20.6 per ct. more 

 acid than sprayed grapes. 



The destruction of hibernating places of the grape leaf -hopper 

 is recommended as a method of control, especially to save the 

 young foliage of the grape in the spring. 



When hibernating adults are on the young foliage, delaying 

 the removal of the young shoots at the base of the vine will 

 tend to keep the insects on the lower leaves and thus afford some 

 protection to the more permanent foliage. The lower shoots 

 should be removed just previous to spraying. 



INTRODUCTION. 



Experiments to develop efficient spraying practices to control 

 the grape leaf-hopper have been conducted for three seasons and a 

 part of the results of this work have been published.* During 

 the past year additional facts have been gathered which have to do 

 largely with the hibernating and early spring habits of this insect. 

 These studies have emphasized the importance of certain control 

 measures which are designed principally to protect the young 

 foliage of the grape during the latter part of May and June when 

 it is impracticable to attempt to combat the pest by spraying. 

 Moreover the increasing use of cover crops, due to the recommen- 

 dations of the Horticultural Department, has prompted some 



N. Y. Agr. Expt. Station Buls. Nos. 331 and 344. 



