BULLETIN 198. 



THE GRAPE LEAF-HOPPER. 



211 



galvanized mosquito wire-netting over a square frame of wood or 

 laths or other light material. A single covering of mosquito netting 

 will allow some hoppers to escape through the mesh. If it is obtainable, 

 a 20-mesh screen would be preferable. Ordinary galvanized mos- 

 quito wire-netting, however, can be obtained almost anywhere, and 

 two layers of it work very satisfactorily. The bottom of the cage 

 consists of a shallow tray. This is made by turning up about an inch 

 or an inch and a half of the edges of a sheet of light galvanized iron. 

 There are two grades of this iron, and the heavier grade adds much 

 more weight than 

 is necessary. One 

 side of the box is 

 kept open and there 

 is a V-shaped open- 

 ing (Fig. 22) in the 

 tray at the bottom 

 which permits the 

 cage to be pushed 

 on to the vine. At 

 the same time that 

 the cage is swung 

 into position the vine 

 is bumped by the 

 base of the opening, 

 which is padded 

 with leather, thus 

 jarring the hoppers 

 off. The sides and 

 bottom of the cage, 

 having been pre- 

 viously smeared 

 with crude oil, catch 

 all the hoppers that 



fall on to them. The cage should be operated with the open side facing 

 the direction from which the wind is blowing. If there is a breeze 

 blowing, very few will escape on the open side. However, if there is 

 no breeze, and the hoppers are especially active, a canvas curtain 

 fastened on the front of the cage at the top can be very readily dropped 

 down as the cage comes into position, thus shutting off all possibility 

 of escape. 



The bottom of the cage is a very essential feature, since most of the 

 hoppers drop to the bottom at the back of the cage or are caught within 

 a foot or two from the bottom on the sides. To prevent any escaping 

 by dropping down through the opening in front of the vine this may 



Fig. 22. 



The hopper cage with the V-shaped opening at 

 the bottom covered with canvas. 



