EXPERIMENT STATION WORK WITH INSECTICIDES. 261 



the same factory contained 30 and 58 per cent of water and 24 and 40 

 per cent of actual soap, respectively. The variation in commercial 

 composition of whale-oil soaps appears to he so great that the 

 orchardist can not be sure of obtaining!: a uniform strentjth of solu- 

 ti(m from a fjiven fornnda, and it is observed that the lack of 

 uniformity, therefore, seriously ati'ects the value of these substances 

 for spraying purposes. In order to obtain a soap of uniform com- 

 position, it is reconnuended that the necessary materials be ])ur- 

 chased and combined at home. For this purpose a formula calling 

 for G pounds caustic soda, 22 pounds fish oil, and H gallons of water 

 is recommended. This is sufficient to make 40 pounds of soap which, 

 when used at the rate of 1 pound in 7 gallons of water, gave com- 

 pletely satisfactory results on the foliage of apple, i^ear, cherry, and 

 peach trees, and currant bushes. In all cases plant lice were de- 

 stroyed and no injury was observed from the soap. In further ex- 

 periments to determine the elfect of free alkali, soaps were made so 

 as to contain from 1 to 50 per cent of free alkali. It was found that 

 injury was done as soon as the amount of free alkali reached 10 per 

 cent. In soaps containing 5 per cent or less of free alkali little dam- 

 age was caused to the foliage. Homemade soap as recommended l)y 

 the New York State Station can be made for about 2 J cents per pound, 

 and has the great advantages of uniform composition, reliability, and 

 cheapness. 



SPECIAL INSECTICIDE METHODS. 



THE CODLING MOTH. 



The codling moth is a serious enemy of the apple in almost all 

 localities where that fruit is grown. The various experiment stations 

 have, therefore, been called upon to carry on investigations on the life 

 history, habits, and means of combating the pest. In California " 

 various methods of controlling the codling moth were tested, but the 

 only one which offered any prospect of good results was the use of 

 arsenical sprays. For this purpose Paris green proved as effective 

 as any other arsenical, and gave satisfactory results when used at the 

 rate of 1 i)ound per 150 gallons of water. In localities where injury 

 is observed from Paris green this may be avoided by the addition of 

 ai)out five to ten times as much lime as the (juantity of Paris green 

 used. Lime arsenite and lead arsenate are reconnuended for sul)- 

 stitution in the place of Paris green where the latter burns the foliage. 

 During experiments carried out in California, arsenate of lead was 

 found to be by far the safest of all the arsenicals tested, but is less 

 fatal to the codling moth, and nnist, therefoi'e, be usecl in hii-ger 

 quantities. A mixture of Paris green, oil, and lime was also tested. 



oCaiifonii.-i st;i. r.iii. ir»r>. 



