87 



Results of applications of insecticides made in Curtis Park, Denver, for the cot- 

 tony map^e scale. 



[Treated November 23, 1903; examined February 27, 1904.] 



Results of later applications in Curtis Park. 

 [Treated February 19, 1904; examined March 1, 1904.] 



Insecticide. 



Lime-sulphur-salt (Illinois for 

 mula). 



Kerosene emulsion. 



Do 



Do. ". 



Do 



Do 



Do. 



"Whale oil soap (hard) 



Do ... 



Do 



Do. 



Do 



Check 



Strength. 



Full . 



50 per cent 



33 per cent 



25 per cent. 



17 per cent 



12 per cent 



10 per cent 



1 pound to 1 gallon . . 

 1 pound to 2 gallons . 

 1 pound to 3 gallons . 

 1 pound to 4 gallons . 

 1 pound to 8 gallons . 



Remarks. 



PREPARATION OF INSECTICIDES. 



The kerosene emulsion was emulsified with whale-oil soap. The 

 tobacco stems were very dry when weighed and were boiled one hour 

 in enough water to cover them, after which the concoction was 

 diluted to the strengths given. The tree soap employed was used in 

 the first series of experiments and hard whale-oil soap, purchased at 

 a drug store, in the second. The lime-sulphur-salt wash was pre- 

 j^ared according to the Illinois formula and boiled three hours. 



APPLICATION OF THE INSECTICIDES. 



Both seneca and vermorel nozzles were used. The latter did 

 good work and is rather to be preferred on account of economy of 

 material. Onl}' the lower branches of the trees were sj^rayed and in 

 some cases two applications were made on diiferent parts of the same 

 tree. With the lime-sulphur-salt wash two entire trees were treated. 



