72 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



demonstrate to the growers that they were not wholly dependent on 

 nicotine solution. A common formula for kerosene emulsion and the 

 one recommended on our spray calendar calls for one-half pound of 

 soap and two gallons of kerosene to make thirty gallons. In this 

 formula the soap seemed to be insufficient for the kerosene, so we in- 

 creased the proportions somewhat. We also doubled the amounts of 

 soap and kerosene but instead of making sixty gallons, diluted it less, 

 to make fifty gallons, the right quantity to fill the spray barrel. Laun- 

 dry soap was purchased by the box at wholesale prices, and the amounts 

 of materials used were as follows: 



Kerosene 4 gallons 



Laundry soap (about 30 ounces) 3 cakes 



Hot water 2 gallons 



After churning, dilute to make fifty gallons. The soap was shaved 

 into thin slices with a tool for shredding cabbages, and was dissolved 

 in water on a stove set up in the field for this purpose. It was then 

 mixed with the kerosene and churned back and forth through a small 

 tube under pressure by means of a bucket pump with the hose directed 

 back into the liquid, after which it was transferred into the pump bar- 

 rel and sprayed upon the plants with hand-power barrel pump with 

 spray rods bent at an angle of forty-five degrees near the nozzles. 



This emulsion was effective, and all aphids hit by the spray were 

 killed. A part of one field was sprayed with nicotine solution and soap 

 for comparison. Some of the men who applied the mixture thought 

 that slight injury was caused by the kerosene emulsion, but the same 

 thing could be detected on some of the plants before they were sprayed. 

 The variety was "Gold Coin," and there were many mosaic plants in 

 the field ; the tissues break down and the leaves turn brown earlier on 

 these plants and this is probably the explanation of the injury rather 

 than the spray. 



A press notice was issued advising growers to spray at once with kero- 

 sene emulsion in order to save their crops, and to show them that they 

 were not absolutely dependent upon nicotine solution. The com- 

 parative costs of the two mixtures are about as follows : 



Kerosene Emulsion 



4 gallons kerosene at .14 (retail) $.56 



3 cakes soap at .06 (wholesale) 18 



Total $-74 



Nicotine Solution 



Nicotine sulphate ("Black Leaf 40") 1 pint (by the gallon) $1.31 



Soap 3 cakes at .06 (wholesale) 18 



Total $1 .49 



