BULLETIN 198. THE GRAPE LEAP-HOPPER. 215 



and are about ready to fall naturally. The chief result of this practice 

 is to drive the hoppers elsewhere for food. In the late fall the adult 

 hoppers are still feeding on the vine foliage, and there they continue to 

 feed until the leaves lose their succulent material and dry up. When 

 sheep are turned in among the vines and the foliage eaten off, the 

 hoppers will either go to an adjoining vineyard that is still in foliage, 

 or simply begin to feed a little earlier on their wide range of winter 

 food plants which may be growing in the vineyard or vicinity. The 

 destruction of the leaves, however, does away with the sheltering places 

 that would be formed by the leaves accumulating in bunches by the 

 wind ; and a clean vineyard is always freer from hoppers in the winter 

 season than one where there is an abundance of leaves or of growing 

 vegetation. But there is nothing to protect such a vineyard from a 

 possible infestation in the spring from the adjoining vineyards. 



Plowing and sheeping, then, result chiefly in partially destroying the 

 food supply over a limited area, and of doing away with possible 

 hibernating places in the bunches of leaves that would otherwise 

 accumulate. The usefulness of such practices will depend largely on 

 how generally they are carried out in a neighborhood, and at best can 

 be counted on simply to reduce the number of hoppers, which, generally, 

 is not likely to be at a point of effective control. 



SUMMARY. 



The grape leaf-hopper is one of the most important insect pests of 

 the vine in California, as may be seen by the most casual observer in 

 the large amount of foliage that dries up prematurely on the vines in 

 many sections of the State each year. 



Life History. The hoppers pass the winter as adult insects on a wide 

 range of food plants that may be growing in the vineyard or vicinity. 



They attack the vine as soon as the foliage appears, and here they 

 remain until the leaves fall in the autumn. 



One month after they begin feeding on the vine, the overwintering 

 hoppers begin egg laying, which is continued over a period of a month 

 or two, after which they die. The hoppers of the spring brood arising 

 from eggs laid in May, become full grown in three weeks, begin egg 

 laying two or three weeks later, and die off in August or September, 

 making the life of this spring brood approximately three or four months. 

 Hoppers arising from eggs laid by the spring brood in June and later, 

 remain on the vine until the leaves fall in autumn. They then take to 

 whatever succulent vegetation may be present in the neighborhood, 

 where they live over winter and attack the vines again in the following 



