380 KePORT of the L>EPARTMEJSfT OF ENTOMOLOGY OF THE 



pear between the 15th and 20th of June. The maximum number 

 of nymphs appeared the last week of June and the first two weeka 

 of July in 1911, but in normal years the maximum numbers ap- 

 pear from about July 4 until the first of August. Spraying should 

 be done when the maximum number of nymphs are present, thus 

 killing the largest number of insects which will usually confine 

 the number of sprayings to one. One must judge the time by 

 watching the development of the insects. 



(2) The proper cotvtact insecticide must he used and at the 

 proper strength. — The experiments mentioned before show that a 

 nicotine solution diluted until there is 2/lOQ of 1 per et. nicotine 

 in the spray material will kill the nymphs. This means that 

 " Black Leaf 40 " (40 per ct. nicotine) should be used 1 part 

 to 1600 parts of water, and '' Black Leaf Tobacco Extract" (2.7 

 per ct. nicotine) should be used 1 part to 150 parts of water. 

 Other preparations must be diluted according to their nicotine 

 contents. 



(3) Sufjicieni spray mixture must he used to drench the in- 

 sects. — Where the foliage is dense this is accomplished by means 

 of nozzles adapted to throw a large amount of coarse spray. ISToz- 

 zles of the cyclone type with large apertured discs are preferred. 

 The folly of using a fine mist spray when the foliage is heavy has 

 repeatedly been shown since with nozzles throwing such a spray 

 the leaf-hopper nymphs were not killed in sufficient numbers, 

 even though the spraying mixture contained as high as 5/100 

 of 1 per ct. nicotine. 



(4) A pressure of from 125 to 150 pounds per square inch 

 is necessary. — Use a pressure go.ge as the grower may then know 

 the amount of pressure the sprayer is carrying. Applications 

 at low pressure are a waste of time and material. Experiments 

 conducted with a sprayer carrying the automatic leaf-hopper 

 spraying attachment and operating at from only 60 to 80 pounds 

 pressure were failures. 



(5) The under sides of the halves must he thoroughly hit hy 

 the spray. — This means that when the spraying is done by the 

 trailing hose and extensions, the work must be done carefully. 



