SCALE INSECTS OF IMPORTANCE 337 



quite essential to have a potash soap that does not contain more than 

 $0% of water. Such a soap can be secured in large quantities at from 

 3^c to 4c a pound, thus making the mixture cost 7 to 8c a gallon. 

 Soda soaps are difficult to apply in winter on account of the solution 

 being gelatinous when cold. Experiments with both Good's and Leg- 

 gett's whale oil soaps gave httle or no difference in their insecticidal value. 

 Good's soap dissolved much easier and was less difficult to spray. 



Whale oil soap and crude petroleum combination. Experi- 

 ments with a combination of whale oil soap and crude petroleum, did not 

 give as good results as were obtained with a plain 20% crude petroleum 

 emulsion. This compound was obtained by dissolving a pound of whale 

 oil soap in each 4 gallons of water and putting the mixture in the barrel 

 of a "kerowater" sprayer.^ Crude petroleum was placed in a tank and 

 the pump set to deliver 10% oil, thus obtaining a whale oil, petroleum 

 emulsion. 



Crude petroleum emulsion. Treatment of the pernicious or San 

 Jose scale in early spring with a 20% mechanical emulsion of crude 

 petroleum, using a "kerowater" sprayer, was found even more satis- 

 factory than the whale oil soap solutions, and so far it appears not to 

 have injured the trees in the slightest degree. The petroleum used was 

 the blended product sold by the Standard oil co. as crude petroleum. 

 It is said to run about 44° on the Beaume oil scale, but a sample of the 

 oil used gave a reading of but 37° while some purchased in December 

 1900 stood at 41.5°. It was tested in 1900 both in an experimental and 

 in a practical way with most excellent results. There is less danger of 

 injuring the trees if a lighter oil is used and it is apparently just as effect- 

 ive as an insecticide. W. H. Hart of Poughkeepsie (N. Y.) obtained 

 most excellent results on a large scale with a mechanical dilution of crude 

 petroleum purchased of the Frank oil co., Titusville (Pa.). This oil runs 

 trom a little above 43° to nearly 45° on the Beaum6 oil scale. The 

 mechanical emulsion does not change the nature of the oil, but it enables 

 the operator to cover a tree thoroughly with a minimum amount, and thus 

 there is not only a saving of material but there is less danger of injuring the 

 tree. The crude petroleum spreads readily, adheres to the bark in spite of 

 repeated rains, leaving a glossy coat of the heavier oils, which remains 



iMade by the Gould manufaciuring co., Senaca Falls N. Y. Mecbanioal 

 sprayers are also made by other luanufacturers. It is well to test them wbeu 

 working from time to time by turning the spray into a jar, allowing the oil and 

 water to separate and then to measure the amounts of each. 



