114 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



vine. The base of the V-shaped opening in the* bottom is padded with 

 leather and the vine is bumped and the hoppers jarred oft', at the same 

 time that the cage is being swung into position. The sides of the cage 

 and the tray at the bottom are smeared with crude oil, and the hoppers 

 as they are jarred off are caught in the oil. 



If there is a breeze blowing the cage can be operated with the open 

 side facing the wind and practically no hoppers will escape. If, how- 

 ever, the day is calm and warm and the hoppers are particularly active 



FIG. 4. The hopper cage. 



a curtain can readily be dropped over the open side as the cage is pushed, 

 onto the vine, and it will prevent any from escaping. 



The V-shaped opening which might allow hoppers to drop to the 

 ground in front of the vine can be covered with canvas, as follows: 

 Take two pieces of canvas about the shape of the opening and a little 

 wider. Double this once on itself and between the two layers sew in 

 pieces of three-fourths inch rubber tubing transversely. These are then 

 firmly tacked on the sides of the opening as shown in the figure. This 

 will allow the cage to be pushed in on the vine and the flexibility of 

 the tubing will bring the canvas immediately into position again. 

 This, with the curtain in front, shuts off all possibility of escape. 



This device can be used to advantage only when the vines are headed 



