U. S. D. A., B . E. Bui. 116, Part I. 



D. F. I. I., Issued July 15, 1912. 



PAPERS ON DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



SPRAYING EXPERIMENTS AGAINST THE GRAPE LEAFHOP- 

 PER IN THE LAKE ERIE VALLEY IN 191 L 



By Fred Johnson, 



Agent and Expert. 



INTRODUCTION. 



An insect pest of the grapevine which has increased in abundance 

 and destructiveness in the vineyards of the Lake Erie Valley during 

 the past few years is the grape leafhopper, 

 TypMocyba comes Say (see fig. 1). Pre- 

 liminary spraying experiments were under- 

 taken against this pest at North East, Pa., 

 by the Bureau of Entomology in 1910. 

 Results of the field work undertaken during 

 that season are presented in Bulletin No. 

 97, Part I, of the Bureau of Entomology, 

 together with a brief consideration of the 

 characteristics, habits, and life history of 

 the insect, and also the character and ex- 

 tent of its injury to the vine. For this 

 reason the subject matter of this paper 

 deals entirely with experiments conducted 



during the season of 1911. Readers un- The grape leafhopper 



familiar with the habits of this pest should ( TypMocyba comes var. coio- 



-.,,-, n j , i radensis): Adult. Greatly en- 



consult the paper referred to above. largecL (Author > s illustration.) 



TREATMENT OF NYMPHS OF THE GRAPE LEAFHOPPER WITH 

 CONTACT SPRAYS. 



During the season of 1911 the grape leafhopper was more numerous 

 and destructive to the grapevines in the vineyards of Erie County, 

 Pa., than in 1910. Owing, doubtless, to the higher temperatures 

 prevailing during June and July of this season, the nymphs (see fig. 2) 

 commenced to appear on the leaves at an earlier date, and the develop- 

 ment of the nymphal stages of the insect were more rapid than in 1910. 

 Since it is in this the nymphal period before the insect has developed 



1 



