44 FIRST ANNUAL REPORT OF THE STATE ENTOMOLOGIST. 



A difficulty in the use of kerosene and water is found in the readi- 

 ness with which they separate when at rest, requiring for their union 

 violent and almost constant agitation. In the above applications the 

 mixture was made by discharging the syringe several times into the 

 vessel containing the liquid before each discharge upon the plants. 

 Prof. Eiley has announced the following method of overcoming the 

 difficulty and dispensing with most of the attendant labor : 



Nothing is more deadly to the insect in all stages than kerosene or oils of any 

 kind, and they are the only substances with which we may hope to destroy the 

 eggs. In this connection the difficulty of diluting them, from the fact that they 

 do not mix well with water, has been solved by first combining them with either 

 fresh or spoiled milk to form an emulsion, which iS easily eiHected ; while this in 

 turn, like milk alone, may be diluted to any extent so that particles of oil will 

 be held homogeneously in suspension. Thus the question of applying oils in any 

 desired dilution is settled and something practical from them may be looked for.* 



Experiments made by Prof. Comsfcock do not fully confirm the 

 above statements, as he experienced difficulty in obtaining the emul- 

 sions and in their subsequent dilution to any great extent, as appears 

 from the following extract from his last Eeport : 



An emulsion of kerosene and milk can be easily made by placing the fluids 

 together in a bottle and shaking them violently for several minutes ; about three " 

 minutes is the time usually required. The quantity of milk used should be at 

 least equal to that of the kerosene. The best results were obtained when the 

 kerosene formed only one-third of the mixture, but equal parts of kerosene, milk 

 and water gave as good results as'one part of kerosene to two parts of milk. For ex- 

 ample, in one series of experiments I was unable to make an emulsion of equal 

 pans of oil and milk, but by the addition of a third part of either icater or milk 

 I was able in each case to make a good emulsion. These emulsions were of a 

 thick, creamy consistence and were very stable, no indication of a separation of 

 the oil from the milk in one case, or from the milk and water in the other, being 

 observable even after the emulsion had stood for twenty-four hours. But as soon 

 as water was added to the emulsion in any considerable quantity, the oil, or the 

 oil and milk together, floated on the surface of the water ; and no amount of 

 shaking would serve to mix the liquid so that the mixture would be stable. It is 

 true that in some of the experiments the emulsion separated from the water less 

 readily than oil alone would ; but in each case the mixture was of such a nature 

 that it was necessary to stir it constantly in order to keep the oil suspended in 

 the water. f 



In all cases where kerosene can be used without applying it to vege- 

 tation it is a very valuable insecticide. It may thus be employed in 

 various methods against a large number of insect pests, as for example: 



A small quantity poured in a broad tin basin, either by itself or 

 floated upon water, is serviceable for the collection of the Colorado 

 potato-beetle (where there is an unwillingness to use Paris green and 



* Scientific American, Oct. 16,1880, and American Entomologist, iii, 1880, p. 246. 

 \Ann. Rept. Cominis. Agricul. for 1880, pp. 2S8-9. 



