SPRAYING AGAINST THE GEAPE LEAFHOPPER. 



results to check the development of the foliage and to retard the 

 growth of those new shoots which spring from the canes near the 

 lower wire of the trellis. This early retardation of growth is more 

 important than would at first appear, for it is highly desirable that 

 these new shoots springing from the canes near the lower wire of the 

 trellis should make a thrifty growth during the early part of the 

 season, since it is from them that canes for bearing the next season's 

 crop of fruit are selected. This feeding of the overwintering adult 

 " hoppers " continues for several weeks ; in fact, many of them may 

 remain upon the vines 

 until some of the new 

 generation has ma- 

 tured. 



THE EGG STAGE. 



Egg laying by the 

 overwintering fe- 

 males does not com- 

 mence in the vine- 

 yards of the Lake 

 Erie Valley until 

 about June 1, after 

 the adults have been 

 feeding upon the 

 vines for several 

 weeks. The eggs are 

 deposited on the un- 

 derside of the leaves. 

 They are tucked un- 

 der the skin indis- 

 criminately as to lo- 

 cation on the leaf and 

 are very difficult to 

 locate on those varie- 

 ties possessing a heavy pubescence, as is the case Avith the Concord. 

 The egg stage covers a period of about 10 days to 2 weeks. The period 

 of egg deposition is obviously a long one, since newly emerged nymphs 

 are present upon the foliage from the middle of June until late in 

 October. Observations indicate, however, that the maximum deposi- 

 tion must occur during the last three weeks in June and the first week 

 in July, since the period when there is a maximum number of nymphs 

 upon the leaves is included in a period from the last week in June 

 until about August 1, at which latter date many fully developed 

 nymphs are making their final molt. 

 71419°— Bull. 97—12 2 



Fig. 5. — Grape leaf showing final result of attack by the 

 grape leafhopper ; leaf withered and brown before the 

 fruit is mature. (Original.) 



