216 UNIVERSITY OP CALIFORNIA EXPERIMENT STATION. 



spring. These begin depositing eggs a month after the leaves appear 

 on the vine, and die off in midsummer, making the length of this life 

 cycle approximately one year in the central valleys of California. 



Control. The most satisfactory control method tried during the past 

 two years was the use of the screen cage. This was found to capture 

 about 85% to 95% of the adult hoppers at a time in the spring before 

 any eggs are deposited. 



Spraying for the nymphs about June 1st, or just before the spring 

 brood becomes mature, will kill a satisfactory percentage of the nymphs 

 or young, but will not kill many adults, or prevent eggs, which are 

 present at this time, from hatching later. If the cage method has not 

 been used, or satisfactorily operated, spraying for the nymphs will very 

 materially aid in reducing the numbers of the spring generation. 



Plowing or other farm practices can not be relied upon, but when 

 such measures are generally practiced throughout a neighborhood, they 

 may aid in reducing the numbers somewhat. 



