2 BULLETIN 480, IT. S. DEPARTMENT OF AGRICULTURE. 



poisons at that time was not regarded as an important factor. The 

 State Board of Agriculture of Massachusetts later conducted ex- 

 periments with insecticides which resulted in 1S9J: in the develop- 

 ment of arsenate of lead as the most economical and effective poison 

 for control work against leaf-eating insects. After these demonstra- 

 tions, spraying became more general, owing to resulting effectiveness 

 as well as to a considerable reduction in expense, and this naturally 

 led to the modification and improvement of machinery and appa- 

 ratus for applying mist sprays. 



In 1895 the late J. A. Pettigrew, while superintendent of Prospect 

 Park, Brooklyn. N. Y., began solid-stream spraying, and in the 

 Yearbook of the United States Department of Agriculture for 1896 

 there appears an article by Dr. L. O. Howard on the subject. The 

 sprayer assembled by Mr. Pettigrew had steam as its motive power, 

 the pump and engine being connected to a watering cart. (PL II.) 



Owing to the discontinuance of appropriations by the Legislature 

 of Massachusetts, the gipsy-moth work was stopped in 1900, and no 

 State work was carried on in combating this pest until May, 1905, 

 when a further appropriation was made. 



In 1905 the late Gen. S. C. Lawrence, of Medford, who was in- 

 tensely interested in the work of combating the gipsy moth on his 

 large estate and others surrounding it, saw the necessity of larger 

 machines for spraying and purchased a high-power machine which 

 was operated by an air-cooled gasoline engine and had a triplex 

 cast-iron pump. This machine did very good work, but its use indi- 

 cated that further improvements were desirable. 



Through the efforts of the writer, while in the employ of the 

 State of Massachusetts, some important mechanical devices in solid- 

 stream spraying were constructed, and during the last few years, 

 while carrying on the scouting and extermination work for the 

 Bureau of Entomology, United States Department of Agriculture, 

 further improvements have been made. Many of these improvements 

 are now being extensively used in New England, but in order that 

 others contemplating the use of such apparatus may know the most 

 economical and practical methods the following suggestions, illus- 

 trations, and tables are submitted. 



After a careful inspection of the territory surrounding the known 

 infested area in Massachusetts, it was found that it had increased 

 from 359 square miles in 1900 to 2,500 square miles in 1905. It was 

 apparent that a considerable amount of spraying must be done, but 

 the apparatus available for so large an operation was insufficient 

 and indequate, there being hardly any spraying machinery on the 

 market except that principally used for orchard spraying.^ After 

 the first season's work efforts were made to improve spraying ma- 

 chinery, so that the work could be brought to a higher degree of 



