354 Bulletin No. 112. [January, 



much liquid is needed to the tree. On the other hand, the scales are 

 now larger and firmer and more resistant to the insecticide than in 

 summer. 



The extensive operations against this scale by the Superintend- 

 ent of Lincoln Park during the winter of 1905-06 were followed by 

 one of my assistants, Mr. E. O. G. Kelly, sent repeatedly to Chicago 

 for this purpose. Nearly every tree and shrub in this park infested 

 by the maple scale was sprayed under the immediate supervision of 

 Mr. R. W. Braucher. Two thousand six hundred and seventy-three 

 trees and 4456 shrubs were sprayed, nearly half the trees ranging 

 from large to very large, and the remainder from small to medium. 

 The materials used in this treatment were 4153 gallons of kerosene 

 and 3074 pounds of soap, made up in 20,800 gallons of kerosene 

 emulsion. The cost of the latter was approximately 2 cents a gallon. 

 With the outfit used, a Fairbanks-Morse power sprayer with double 

 "Vermorel" nozzles, it required, on an average, five minutes to spray 

 each tree, or an hour for twelve trees. Eight men were employed 

 with the outfit, making an average service of forty minutes of one 

 man's time per tree. Six and seven tenths gallons of emulsion were 

 applied to the average tree, at a total cost of 43 cents for both ma- 

 terials and labor. 



In spraying operations, ladders and long canes were used in or- 

 der that all parts of the larger trees might be reached by the spray. 

 In the greater part of the work 19 and 20 per cent, emulsions of 

 kerosene were applied. To make this up in 200-gallon lots, 20 gal- 

 lons of water and 27 to 30 pounds of "Tak-a-nap" soap were placed 

 in the mixing tub. and steam was introduced until the soap was dis- 

 solved and the solution was boiling hot. Forty gallons of kerosene 

 were then slowly pumped into the tub, and the mixture was pumped 

 back into itself until the kerosene no longer rose to the surface when 

 the pumping ceased. The emulsion was finally diluted by adding 

 hot water to make 200 gallons. 



A part of the trees examined were sprayed between December 

 26 and January 5, and others January 11 and 13 and March 30. 

 The effects of the spray were determined by comparing ratios of 

 dead and living scales on trees which had been treated, with those 

 from others examined at the same time which had received no 

 treatment. A determination of the condition of the scales subse- 

 quent to treatment was a much more difficult matter at this season 

 than during the summer. The dormant insects themselves were 

 comparatively large and dense, and changes due to death were pro^ 

 duced but slowly in the cold midwinter weather. From twenty- 



