382 



ECONOMIC ENTOMOLOGY 



average profit was $4.50. These results are interesting as they were 

 obtained from farmers under ordinary farm conditions. 



DUST SPRAYING 



During the last 6 or 7 years there has been a revival of dust 

 spraying, especially in New York State. Professors Reddick and 



Fig. 249. — A dust sprayer in operation in an orchard. (Courtesy of the Niagara 



Sprayer Co.) 



Crosby of Cornell University carried out a series of experiments from 

 191 1 to 1917 with dust sprays against insects and fungous diseases of 

 the orchard. Different mixtures were used: 



1. Sulphur, 80 per cent.; arsenate of lead, 20 per cent. 



2. Sulphur, 40 per cent.; arsenate of lead, 10 per cent.; finely ground 

 gypsum, 50 per cent. 



