ELM LEAF ROSETTE AND WOOLLY APHID OE APPLE. 343 



can before pouring out any quantity for dilution. In most cases one 

 gallon of the Black Leaf will be found sufficient for each seventy gal- 

 lons of water. But if in the treatment of any louse this does not seem 

 sufficient it may be used in preparation of one gallon to sixty or sixty- 

 five gallons of water. Careful sprayers have usually succeeded in 

 killing plant lice with this preparation in the proportion of one gallon 

 to each one hundred gallons of water. Thoroughness of application 

 is of as much importance as the strength of material used. 



Nikoteen is a more concentrated abstract, I part being used with from 

 400 to 600 parts of water. 



Black Leaf 40 is a concentrated solution of nicotine-sulphate and is 

 widely and successfully used in large western orchards, at the rate 

 of 1 part to 800 or 900 parts of water. 



It is the common practice to add soap, — whale oil soap or good laun 

 dry soap at the rate of 2 bars to 50 gallons. This is to lessen the 

 formation of drops, causing the spray to cover surfaces more in the 

 form of thin film. 



Better success is obtained by some by using a little lime instead of 

 soap, the inert solid in suspension aiding the extract to "wet" and 

 "stick" to the bodies of the aphids. For this purpose 1 pound of 

 stone lime, slaked and strained into 50 gallons of tobacco extract as 

 prepared for application, is sufficient. 



Formula B. — Kerosene Emulsion. 



Hard Soap 1-2 pound 



Boiling Water ■ 1 gallon 



Kerosene 2 gallons 



To prepare dissolve one-half pound of soap in one gallon of soft 

 water by boiling; when well dissolved and still boiling hot, remove 

 from the fire and add two gallons of kerosene, and agitate at once as 

 briskly as possible. The emulsion is more readily made if the Kerosene 

 first be heated by immersing the vessel containing it in a larger vessel 

 of boiling water. Never heat the kerosene over a direct fire. 



If large quantities are being made, a good way to emulsify is to use 

 a force pump and spraying nozzle and pump the mixture as forcefully 

 as possible back into the vessel containing it. If the emulsion is prop- 

 erly formed, the whole mass will appear much like whipped cream and 

 will mix readily in water without a film of oil rising to the top. 



As soon as emulsified, add twenty-seven gallons of water and use at 

 once. This will make thirty gallons of the mixture, and such an emul- 

 sion will be one-fifteenth oil (or a 7 per cent emulsion). This is the 

 strength ordinarily used for the destruction of insects upon plants. 

 For larger or smaller quantities, prepare in the same proportions. 



Sometimes the emulsion is not perfect and a little oil rises to the top. 

 In such cases, if the last in the barrel or tank is pumped out upon the 



