ENTOMOLOGY 71 



leaves prevents the proper assimilation of food by the vines ; the fruit 

 may be materially reduced in quantity and will lack much in flavor 

 and sugar content. Although the yearly loss to grape growers from 

 the attack of this species is sufficient to place it among the first-class 

 pests of the vine, but little effort ordinarily is made to control it, per- 

 haps principally because no very practicable remedy has until re- 

 cently been proposed. 



The adult grape leaf-hopper is quite small, measuring not more 

 than one-eighth of an inch in length. It is very agile, moving with 

 almost equal facility in all directions, and flies out from the vines 

 often in swarms upon slight disturbance. The insect passes the win- 

 ter in the adult condition in hibernation in trash in and near vine- 

 yards, in the edges of neighboring woods, in grass along gullies, in 

 ditches, etc. Early in the spring the insects come from winter quar- 

 ters and attack almost any succulent vegetation at hand. By the 

 time the foliage of the grape appears they are out in large numbers 

 and begin to infest the vineyards. These adult hoppers of the hiber- 

 nating generation feed and breed on the lower or earlier-appearing 

 leaves, gradually disappearing as the season progresses, but not before 

 some of their progeny have reached the adult condition. Some weeks 

 are spent by the adults in the spring in feeding before egg-laying 

 begins. Eggs are placed just beneath the epidermis in the lower leaf 

 surface, usually singly but also in groups of from 6 to 9, the egg 

 stage, according to Professor Slingerland, lasting from 9 to 14 days. 

 Egg-laying probably continues for two months or more. When just 

 hatched the young hopper is very small, whitish in color, with red 

 eyes, later becoming striped with yellow. In the course of their 

 growth these nymphs molt four times the white skins being very nu- 

 merous on the lower surfaces of badly infested leaves. The nymphs 

 feed in the same manner as the parents, sucking juices from the 

 leaves, at first on the lower surface of the older leaves where they 

 were born, but later spreading more or less generally over the plant. 

 They are very agile, running in all directions, but do not leap or hop. 



The grape leaf-hopper has proved to be a difficult pest to com- 

 bat successfully. Various practices have been proposed, such as the 

 use of trap lanterns to burn at night, the raking and burning during 

 winter of fallen leaves and trash in vineyards, the use of sticky shields 

 or fans to catch the adults as they fly from the vine on being dis- 

 turbed, and in California the use of insect nets for the same purpose. 

 Extensive field experiments were made by Professor Slingerland. 

 He found that large numbers of the hibernated adults could be 

 caught on sticky shields carried along each side of the row, the in- 

 sects being frightened out by disturbing the vines. This work is done 

 oarly in the season, before oviposition takes place to any extent. A 

 light wooden frame is made, 7 or 8 feet long by 4 feet high. To the 

 crosspiece at the bottom, which should be up from the ground about 

 a foot, are fastened several stiff wires of the shape of a hayrake tooth. 

 These are fastened so that the points curve inward and downward to 

 the ground at base of plants when the shield is held in place beside 

 the vines. The whole framework, including the wires, is covered 



