REPORT OF COMMITTEE ox PUBLICATION 195 



cause of being washed upon the ground. Careful forecasting of the weather 

 is necessary if best results are to be attained, but under the proper condi- 

 tions, this material followed with the Bordeaux mixture and poison has pro- 

 duced the best results of any tried to date. 



From the results of many field trials and observations we would recom- 

 mend that when a vineyard is severely infested the molasses and poison be 

 used for the first spraying and the second application be Bordeaux mixture 

 and poison, while in a vineyard having a moderate infestation two applica- 

 tions of Bordeaux mixture and poison be used. 



The fungicidal qualities of this latter spray are needed in most New 

 York vineyards and at least one application should be made whether insects 

 are present or absent. 



THE GRAPE LEAF-HOPPER. 



By F. Z. HARTZELL, 

 Vineyard Laboratory, Fredonia, New York. 



The most common insect found en grape vines in the United States is a 

 small insect commonly, but wrongly, called "thrips" in many localities. This 

 is the grape leaf-hopper and a number of species are found on cultivated 

 grapes. The species most often found is Typhlocyba comes Say of which 

 there are nine varieties. Inasmuch as the other species are similar to this 

 one in life habits and destructiveness and also because this species has been 

 studied by entomologists to a greater extent than the others, this paper will 

 be confined to the life history, habits, destructiveness and control of Typhlo- 

 cyba comes Say as found to exist in the Lake Erie Valley and throughout 

 the Empire State. Due allowance must be made for differences which exist 

 regarding dates of transformation, etc., in other parts of its range. ' 



The other species and varieties being similar in habits to the typical 

 comes, control measures adapted to the latter form will apply to the other 

 species at least under New York conditions. Certain varieties of grapes are 

 preferred by one species of leaf-hopper and appear to be avoided by others. 

 Again, several species may infest the same variety in a region but this is not 

 a constant habit, for Concords in one locality are infested by T. comes in 

 another by T. tricincta or a variety of T. comes. Since a detailed discussion 

 of these facts would lead us beyond the limits assigned to this paper we will 

 confine our writing to the life history of T. comes and especially to the 

 factors necessary to a knowledge of the proper control of the several species 

 of leaf-hopper found in the northeastern United States. 



Food Plants. 



Although the grape leaf-hopper feeds on the foliage of the grape during 

 practically the entire period that this is present, it also feeds on other plants 

 in the spring before the grape foliage has unfolded and during the fall after 



