208 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



sulfur on a piece of burlap sacking was placed between every four 

 vines over about one quarter of an acre, and the sulfur burned. The 

 hoppers apparently suffered no discomfiture, but the foliage on the 

 windward side of the vines was badly burned. 



Sprays and Washes. Various kinds of sprays and washes were 

 tried 'for killing the adult hoppers in the spring, and also during the 

 winter while they were still on their winter food-plants. None of 

 these were successful because of the activity of the hoppers, for it was 

 impossible to drench those in the air thoroughly enough to kill them. 



Fig. 19. Spraying for the nymphs. 



Pure kerosene was used while they were still on the vegetation in 

 winter, and even with this strong material probably the larger per cent 

 escaped on account of their activity. They could, however, be quite 

 readily killed if they were against something, as the ground or a leaf, 

 where the spray would wet them thoroughly. 



Spraying for the nymphs, however, is a different problem, and it 

 is practical to get a very large per cent of them by this method. The 

 nymphs are all on the underside of the leaves and they are not capable 

 of flying or jumping, so that it is possible to hit them with a spray. 

 The sprays which gave the best results were the whale oil soap solution 

 and the resin spray, the soap solution being probably a little the better. 



