METHODS Now USED IX FIGHTING THE GIPSY MOTH. 65 



500 tons of this poison were used to New England for spraying the 

 trees. Considerable spraying was done to destroy the elm leaf- 

 beetle (GaleruceUa luteola Mull.), and this poison was used exclu- 

 sively to the work. The best results are secured to spraying for the 

 gipsy moth when the caterpillars are very small, but to covering 

 large an area it is impossible to provide machines enough to do all 

 the work early in the season. Ten pounds of arsenate of lead to 

 100 gallons of water is a satisfactory strength to use, but after the 

 caterpillar- are half grown it is often desirable to increase this amount 

 to 12 or 15 pound- to the same amount of water. Spraying late to 

 the season after the larvae are nearly fullgrown is of doubtful advan- 

 tage, as the caterpillars are very resistant to poison, and as a rule 

 will pupate and transform to moths. 



The power spraying machines used to 1909 were superior to every 

 way to any that had been designed previously, and plans for im- 

 provements on these machines have been considered for the work 

 next season. Barrel sprayers fitted with hand pumps are used to 

 **>me extent for treating shrubbery and orchards, and in some cases 

 i*igh tree- are treated by using these outfit-, especially when it is neces- 

 sary to prevent buildings from becoming discolored by the poison. 

 The use of these small outfits is impracticable when it is necessary 

 to cover to a period of six weeks the large areas which must be 

 sprayed, and a- a result of varied tests of power outfit- a system has 

 been devised for using what i- known a- " solid-stream spray." 



About 1895 Mr. J. A. Pettegrew. who was then superintendent of 

 Prospect Park, Brooklyn. X. Y.. c istructed a steam spraying outfit 

 for use in treating the tree- which were being severely injured by the 

 elm leaf-beetle. Sufficient pressure was developed to spray high 

 trees from the ground, the shape of the nozzle being such that a solid 

 stream wa- carried high in the air. where it was broken into a mist. 

 This -piayer wa- described and illustrated by Dr. L. O. Howard in 

 an article on -praying. a Soon after Mr. Pettegrew became superin- 

 tendent of the Bo-ton city parks he used a similar outfit for spraying. 



In 1 905, this method of treatment wa- tested by Gen. S. C. Law- 

 rence, of Medford, Ma--., who wa- carrying on extensive spraying 

 operations to protect the tree- from the gipsy moth. This outfit 

 wa- built by a Boston firm, and was equipped with a high-power 

 gasoline engine instead of with steam to generate power. The 

 experiment wa- successful and since that time the use oi outfit- built 

 on the same general line- has been gradually increasing. Mr. ( ieorge 

 II. Kermeen. one of the representatives of the firm alluded to. was 

 an early advocate of tin- system of -praying, and in addition to 



""Tin- use of Bteam apparatus for spraying," Yearbook, I . S. Department of 

 Agriculture, L896. 



40706*- Bull. 87- -10 5 



