ISTew York Ageiculturat, Experiment Station. 3T5 



LIFE IIISTOEY. 



Emergence in the spring. — When the "warm spring days cause 

 the various perennial weeds and other plants to begin growth, the 

 grape leaf-hopper seeks these and feeds upon them, but prefers 

 plants belonging to the bush fruits. They feed on these until the 

 new growth of the grape vines has started, when they migrate to 

 them and feed particularly on the shoots and leaves nearer the 

 ground. It is the lower portion of a vine that first shows the 

 results of leaf-hopper infestation, and the infested leaves turn 

 yellow early in the summer. As the season advances and the lower 

 growths become seriously injured the adult " hoppers " attack the 

 leaves higher on the vines. 



Egg stage. — The leaf-hoppers seek the vines during the first 

 two weeks in May and, after feeding for a short time, copulate. 

 The eggs are laid in the tissues of the under sides of the leaves 

 and are so carefully hidden under the epidermis that they are 

 difficult to find. June is the month in which most of the eggs 

 are laid and these give rise to the first brood of n^Tuphs. In an 

 advanced season oviposition may commence as early as the first 

 week in June, but if the year is backward the first eggs may not be 

 deposited until near the middle of this month. The number of eggs 

 deposited reaches its maximum in the latter part of June. Since 

 many of the old hoppers are still alive on the vines when the 

 nymphs reach maturity, it is rather difficult to determine the time 

 of last egg-laying of the over-wintering adults. Of the eggs which 

 are deposited during August the majority undoubtedly are laid by 

 the new brood of adults. The second period of egg laying may 

 last until the middle of September. 



Nymphal stage. — During 1911 the first nymphs appeared June 

 12, and the maximum numbers were on the vines by July 1. 

 ]\rany were changing to adults about July 15. During the latter 

 part of August large numbers of nymphs in various stages o£ 

 development were again obsen^ed. Individuals of the first instar 

 were observed as late as October 1. There is little doubt that the 

 long warm summer =;eason of 1911 produced two distinct broods. 



