140 Control of Parasites 
ous forms which such apparatus might take. A full dis- 
cussion may be found in the Yearbook of the United States 
Department of Agriculture for 1896, and in other publica- 
tions, notably of the State Entomologists, various combina- 
tions are proposed.* 
Since the spray mixtures are very corrosive, the apparatus 
should be thoroughly cleaned immediately after use by 
forcing pure water through it and 
wiping off the exposed parts. 
Failures in results from spraying 
come either from unsatisfactory ap- 
paratus, such as lack of an agitator 
on the pump, poor nozzles throwing 
a shower, instead of a mist, insuff- 
Fic. 54.— “Gem” nozzle cient and variable pressure, or else 
holder. unsatisfactory application, lack of 
thoroughness, failure to choose the right time or weather 
(wind and rain), and use of wrong materials, or improperly 
mixed ones. 
As to the cost of spraying, the Entomologist of the Depart- 
ment of Agriculture estimates that, after a proper apparatus 
is installed, for a city like Brooklyn, N. Y., an expenditure 
of $4,000 to $5,000 would result in green shade trees all 
through the summer, and this expenditure would probably 
not need to be continued annually. The cost must neces- 
sarily vary according to the number and size of trees to be 
treated and to other circumstances, reported experiences 
1 Reliable dealers in spraying machinery are: Gould Manufacturing Co., 
Seneca Falls, N. Y.; Field Force Pump Co., Elmira, N. Y.; Sydnor Pump 
and Well Co., Richmond, Va.; Morrell & Morley, Benton Harbor, Mich.; 
Deming Co., Salem, Ohio; E. C. Brown Co., Rochester, N. Y.; Spraymotor 
Co., Buffalo, N. Y., and London, Canada; Rochester Spray Pump Co., 
Rochester, N. Y¥.; Friend Mfg. Co., Gasport, N. Y.; Hardie Spray Pump 
Mfg. Co., Detroit, Mich.; Wm. Stahl, Quincy, Ill. 
