CONTACT INSECT SPRAYS 199 



more or less readily with water. They are intended for use only 

 on dormant trees and in particular for fighting the San Jose 

 scale, and for this purpose the writer has found them very 

 satisfactory indeed. They have the advantage over lime-sulfur 

 that they are much less disagreeable to apply, which is certainly 

 an important consideration. They will also ' ' creep ' ' on the sur- 

 face of the branch, thus insuring a somewhat better distribution. 

 While these oils are usually bought already prepared, they can 

 be easily made at home and frequently at some saving in cost. 

 However, the commercial forms are usually so satisfactory and 

 they are sold so cheap that it is doubtful whether it would pay 

 the grower to make his own. It certainly would not except 

 where he is in the orchard business in a large way. 



Whale Oil Soap. — A second material frequently used for 

 sucking insects is whale oil soap, which comes as an ill-smelling, 

 sticky, brown soap. Only very distant relatives of the whale 

 enter into its manufacture, as any cheap fish-oil is used in making 

 it. For orchard use it is well to prepare it beforehand by boiling 

 the soap with a certain quantity of water. This gets it into a con- 

 dition where it will readily mix with water when wanted for use, 

 and if this "stock solution" is made at the rate of two or three 

 pounds per gallon it is a very simple matter to prepare a batch 

 of spray for use in the orchard. It is generally used at the rate 

 of one pound of the soap to about 8 to 10 gallons of water. 



Kerosene emulsion, is another \Qvy efficient remedy for such 

 insects as the aphis. The chief objection to it is that it requires 

 a special operation to make, but that is certainly not a serious 

 matter. The formula is as follows : 



^/4 pound of hard soap, 1 gallon water, 2 gallons kerosene. 



Cut up the soap and dissolve it in the water by boiling. Then 

 remove from the fire and add the kerosene; reheat and agitate 

 the mixture violently. A good way to do this is to have a small 

 pump, and pump the liquid back into itself until a creamy white 

 mixture is produced. This is a "stock solution," and ought to 

 keep for weeks or even months without the oil separating out. It 

 is diluted for use according to the insect to ])e attacked. With 



