24 STATE BOARD OF AGRICULTURE. 



cally the instant they become covered or wet, and the sooner the oil 

 gets off thereafter the better it will be for the tree. 



The application of pure kerosene is not advised however at present, 

 because the crude oil is safer and more effective in winter, and a 

 diluted mixture is just as effective in summer. 



Kerosene may be diluted with water either by first emulsifying 

 with soap-suds or by applying with an emulsion sprayer in a mechan- 

 ical mixture. 



The emulsion may be made as follows : 



Hard soap shaved fine (Ivory is best), y 2 pound. 



Water, 1 gallon. 



Kerosene 2 gallons. 



Dissolve the soap in boiling water, warm the kerosene and add the 

 boiling hot suds to it ; then churn with a force-pump for a few 

 minutes, and we get, first, a milky appearance which yields rapidly 

 to a cream, and then to a soft butter-like mass that cannot be pumped. 



When cold this will adhere to glass without oiliness, and the emul- 

 sion thus made, containing 66% of kerosene, may be diluted with 

 water to any desired extent. The water should be soft, or should be 

 made so with borax, and the mixture must be hot to combine to the 

 best advantage. At the rate of i part of emulsion to io parts of water 

 this emulsion is fatal to most insect life except scales, and safe on all 

 save peach trees. The presence of the soap, checking the rapid 

 evaporation of the oil, makes this proportionately more dangerous 

 than even pure oil and much more harmful than mechanical mixtures 

 at greater strength. 



The mechanical mixture is put on by means of a pump or pumps 

 adjusted to draw from separate tanks of kerosene and water at one 

 time, in varying proportions. It is by far the best method of using 

 the kerosene, and a mixture containing io% of kerosene is safe on 

 foliage of any kind in reasonable application, while it is fatal to all 

 insect life except scales. 



There are other ways of using the oil — with pyrethrum, or emulsi- 

 fied with soft soap ; but practically one or the other methods above 

 described will prove satisfactory for general work. Whale-oil soap 

 may, however, be substituted for the ivory soap with some addition 

 to the killing power of the mixture. 



Soaps are insecticides either because they are caustic and corrode 

 the insect, or because they form a film of soap over the spiracles and 

 choke it. Both results are obtained in strong mixtures of any soap,. 



