Insect and Fungous Enemies of the Grape. 17 
It is of the utmost importance that the first treatment be made at a 
time when the first-hatched nymphs are near the last molt and before 
they have developed wings. This will insure the destruction of the 
maximum number of the still younger insects. This time can be deter- 
mined by examining the hoppers on the lower surface of the leaves. 
The earliest full-grown nymphs at this time will have the wing pads 
Fic. 15.—Showing excellent condition of foliage and fruit as a 
result of spraying for the grape leafhopper. 
reaching nearly or quite one-half the length of the body (fig. 12, ¢). 
For the Erie-Chautauqua grape belt this will be in ordinary seasons 
during the second and third weeks of July. One thorough, forceful 
spraying will so check the insects that further applications will be 
unnecessary. In fact, later applications have relatively little value, 
owing to the presence of many adults, which fly from the plants upon 
the least disturbance. 
48533°—21—Bull. 1220-3 
