BULLETIN 192. INSECTS INJURIOUS TO THE VINE. 113 



twenty days to hatch. Then the young or nymph appears and begins 

 at once to feed upon the leaves. It is a very small creature, white in 

 color, with conspicuous red eyes. After feeding for a few days it 

 molts or sheds its skin. Altogether it molts five times, requiring a 

 period of from seventeen to twenty days before the last molt, when the 

 full-fledged winged hopper is produced! 



After feeding for a couple of weeks as an adult hopper, pairing begins 

 and a week later another set of eggs is deposited. These require but 

 from eight to twelve days to hatch, a shorter period than the first lot 

 required, probably on account of the higher temperature later in the 

 summer. Thus the life cycles are repeated. Nymphs arising from the 

 eggs laid by the over-wintering hoppers began appearing about the 

 middle of May, and those from the following brood about the middle 

 of July, making two broods during the season. 



CONTROL MEASURES. 



Farm Practices. Since the over-wintering hoppers are sheltered 

 in large numbers by the leaves which are blown together in bunches 

 in the vineyard, and other rubbish along the borders, clean culti- 

 vation will help to reduce their numbers. The hoppers depend 

 for food upon what they can obtain in the vineyard or vicinity, and if 

 the weeds and other vegetation are kept down many will starve or be 

 obliged to go elsewhere for food. When the vineyard is plowed in early 

 spring before the vines come into foliage, the hoppers will all leave the 

 vineyard and feed upon the nearest available vegetation, which is 

 usually about the borders. If these borders and roadsides could be 

 kept free and a general movement for clean culture inaugurated in a 

 neighborhood, it might do much to prevent the hoppers from becoming 

 excessive, but because of the possibility of extensive migrations in the 

 spring the work of any individual grower might be of little avail, 

 though such migrations did not occur at Lodi the present season and 

 individual work would undoubtedly have been useful. 



The Hopper Cage. So far as the work has progressed this year the 

 most satisfactory method of control is in the use of a hopper cage to be 

 used in the early spring when the young shoots of the vine are about 

 four or five inches long. This is to be supplemented, if necessary, by 

 spraying for the first brood of nymphs early in June. 



The hopper cage (Fig. 4) consists of a frame work of laths over which 

 is tacked a double layer of mosquito wire netting or a single 20-mesh 

 wire screen. The bottom consists of a shallow pan or tray made by 

 turning up about an inch of the edges of a sheet of light galvanized iron. 

 One entire side of the cage is left open, and there is a V-shaped opening 

 in the tray at the bottom which allows the cage to be pushed over the 

 2 BUL. 192 



