10 



sprays are affective by reason of a caustic or burning action 

 upon the body of the pest, or by reason of a smothering effect 

 resulting f rom the closing of the small breathing apertures situa- 

 ted along the sides of the inseet's body. Fig. 3. 



KEROSENE EMULSIÓN.— This material is probably the 

 most generally used of the contact sprays. The stock emulsión is 

 prepared as follows: 



English Metric. 



Kerosene 2 gals. or 7.6. litres 



Soap (ordinary laundry soap or solid 



whale oil soap) % Ib. or 340.5 grams. 



If potash whale oil soap of other soft 



soap is used take .... 1 quart or 1 litre. 

 Water . 1 gal. or 3.8 litre. 



Heat the water to boiling point, and dissolve the soap in it. 

 Remove from the fire and while still boiling add the kerosene and 

 agitate vigorously until a white creamy mass is formed from 

 which the oil does not sepárate. One of the best ways to make 

 the emulsión is to pour the soap solution and kerosone into a 

 sprayer and pump the liquid back into itself. If the pump 

 is not available, possibly one of the mo^t convenient substitutos 



