﻿THE GKAPE LEAFHOPPER IN THE LAKE EKIK VALLEY. 







berries in the cluster, and in a deficiency in the sugar content of the 

 fruit. For these reasons the aggregate injury by this pest during the 

 season of 1912 was fully as great as in that of 1911. 



Thus far mention of the destructiveness of this pest lias been con- 

 fined to the vineyard areas of the Eastern States. For more than 25 

 years this species, Typhlocyba comes, including a western variety, 

 coloradensis (fig. 5), has caused an enormous amount of injury to the 

 grapevines in the vineyards of California, where it has been recorded as 

 an injurious grapevine pest since 1875. Prof. H. J. Quayle, in Bul- 

 letin 198 of the California Experiment Station, states in regard to its 

 destructiveness that "with the exception of the Phylloxera, the vine 

 hopper is undoubtedly the most destructive insect pest of the vine in 

 the State. It is more uniformly present than any other insect attacking 

 the vine, and each year in some parts of the 

 State it occurs in very great numbers, and 

 in such sections it levies a heavy tax upon 

 the vineyard interests." 



Thus it is evident that, taken in the aggre- 

 gate, the injury sustained by the vineyard 

 industry of the East and the West must 

 amount to an enormous sum. It should be 

 remembered, too, that the injury caused by 

 this pest is not confined to the crop of a 

 single season. It frequently happens that a 

 heavy infestation of one or two seasons' 

 duration may so stunt the growth of the vine 

 that its full fruiting capacity may be re- 

 duced for several seasons. In fact, if special 

 efforts for the resuscitation of badly injured 

 vines are not undertaken they may never re- 

 gain their former productive value. Hence 

 the loss to the vineyardist not only consists 

 in the crop shrinkage, but also in the additional cost of the fertiliza- 

 tion and care required to get the vine back into full bearing condition. 



Fig. 5. — A western variety of the 

 grape leafhopper, Typhlocyba 

 comes var. coloradensis: Adult. 

 Greatly enlarged. (Author's 

 illustration.) 



ALLIED SPECIES. 



In the region known as the Chautauqua and Erie grape belt, which 

 includes a narrow strip of territory stretching along the southern 

 shore of Lake Erie from Silver Creek, N. Y., to Harbour Creek, Pa., 

 there are approximately 40,000 acres of vineyard, over 90 per cent of 

 which are of the Concord variety. The species of leafhopper found 

 in injurious numbers in the vineyards throughout this region is 

 Typhlocyba comes. Although occasional specimens of other varie- 

 ties and species may be found, their presence in numbers sufficient to 

 10037°— Bull. 19—14 2 



