414 FRUIT INSECTS 



proportion of the nymphs as possible in early July, when the 

 maximum number is present on the foliage and before many 

 have transformed to adults. The nymphs are then easily 

 killed by contact insecticides, the only difficulty being in hitting 

 them on the under side of the leaves with the spray. At present 

 the most satisfactory results have been attained by thorough 

 spraying with "Black Leaf 40" tobacco extract, 1 part to 1000 

 parts of water. This mixture will kill all the nymphs thoroughly 

 wet by the spray. For efficient work it is necessary to use a 

 pressure of 125 to 150 pounds per square inch, and care must be 

 taken to hit tlu^ under sich^ of every leaf on which the nymphs 

 are feeding, A fairly coarse spray is desirable, and nozzles of 

 the cyclone tyjje having disks of large aperture have given th(^ 

 l)est results; a fine mist s|)ray will not wet the nymphs thor- 

 oughly enough to do good work. Sprayers fitted with fixed 

 nozzles as are commonly used for vineyard work cannot be used 

 against the grape leaf-hopper, as it is impossible to arrange the 

 nozzles so as to hit the under side of the leaves with the spray. 

 Efficient work, how^ever, can be done by having one or two men fol- 

 low the sprayer on foot, carrjdng a four-foot extension rod at the 

 end of which one or two nozzles are so attached as to be directed 

 upward. The extension rod is connected with the pump by a 

 piece of hose 15 or 20 feet in length. By driving slowly and by 

 having careful men to do the work thoroughly, satisfactory 

 results in the destruction of the nymphs and the protection of 

 the crop can be attained by one properly timed spraying. 



The Geneva Agricultural Experiment ' Station has recently 

 perfected a method of spraying for the grape leaf-hopper, by 

 which the necessity of having men to carry the nozzles is dis- 

 pensed with. Here the nozzles are mounted on swinging booms 

 which are hinged to more or less rectangular frames of f inch 

 iron pipe attached to the sides of an ordinary vineyard sprayer. 

 There are three booms on each side of the sprayer, each carrying 

 a nozzle near the end arranged to throw the spray upward. 



