New York Agricultural Experiment Station. 2 



£i I 



ENTOMOLOGICAL DEPARTMENT. 



The grape leaf-hopper.— Bulletin No. 359 is a report of studies 

 on the hibernating habits and spring food plants of this insect, 

 and of various experiments to establish efficient spraying practices. 

 As large numbers of the adults went into hibernation during the 

 fall of 1912, unusual opportunities were afforded for studying the 

 insects under winter conditions. Observations showed that the 

 most favorable hibernating places for the leaf-hopper are fence 

 rows, woods, brush and waste land, weeds or situations where leaves 

 accumulate by the wind. Grass which has lodged also affords 

 winter shelter to the insects. It was moreover determined that the 

 drier, well-drained soils are more conducive to the safe wintering 

 of the adults than the heavier soils. It is believed that green cover 

 crops do not afford suitable hibernating places for the grape leaf- 

 hopper, at least during severe winters. 



Studies on the food plants of the leaf-hopper show that it feeds 

 on the foliage of raspberry, strawberry, blackberry, currant, goose- 

 berry, catnip, Virginia creeper, burdock, beech and sugar maple 

 before it seeks the grapes. Strawberry and raspberry are the pre- 

 ferred spring food plants. The insects migrate from strawberry 

 to the raspberry during early May and from the raspberry to the 

 grape during the latter part of May. 



The foliage of the grape is injured by the overwintering adults 

 but most of the feeding is restricted to the lower leaves, especially 

 those on the young shoots or suckers at the base of the vine. The 

 amount of injury to vineyards varies directly with their proximity 

 to favorable hibernating places and spring food plants. 



Spraying experiments during 1912 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 attachment 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 to 20.6 per ct. more acid than sprayed grapes. 



The destruction of hibernating places of the grape leaf-hopper 



