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UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



Screens or Cages. In our work of spraying for the adults it was 

 soon determined that, if a spray was to be used successfully, the 

 active hoppers must be confined within certain limits in order to give 

 time to hit them thoroughly with the spray. The screen cage shown in 

 Fig. 21 was developed as a result of this, it being intended to apply 

 the spray from the open side through a hole in a canvas curtain which 

 could be dropped down as the cage was pushed onto the vine. This 



Fig. 21. A screen cage used to capture the grape leaf-hopper. 



was found to work quite satisfactorily. It was noticed, however, 

 that when the base of the V-shaped opening on the bottom of the cage 

 struck the vine most of the hoppers were jarred off. This suggested the 

 use of a sticky material on the sides and bottom of the cage and jarring 

 them on to this, and thus dispensing with the spray. 



This method of capturing the adult hoppers by means of the screen 

 cage in the early spring proved to be the most successful of all the 

 means of control tried during the season. 



The screen cage is made by tacking a double layer of ordinary 



