Mil 



and sulphur washes, the ratios of living- scales at the end of ten 

 weeks being" a little more than twice as greut for the whale-oil soap 

 as for the other insecticides. These ratios were, however, so small 

 in both cases ^^.^^) scales out of 5,000 for the soap, and J^5 out of 0,000 

 for the washes) that this difference need hardly be taken into ac- 

 count. 



The cost of the lime and sulphur washes is less than one fifth 

 that of the whale-oil soap, amounting to $1.12 per hundrei gallons 

 for the former in our experiments, and to Sb.50 for the latter. The 

 tjuantity of the washes actually used in the Suramerfield experi- 

 uieuts averaged five gallons per tree, at a cost of live and a half 

 cents. This is about the same as the average cost of treatment 

 with the kerosene emulsion, and but a little more than one third 

 the cost per tree of treatment with whale-oil soap Over the 

 emulsion, the western washes have the inestimable advantag-e that 

 thev never injure the tree: and compared with whale-oil soap they 

 are not only much cheaper and slightly more etTective, but they are 

 also to be preferred because tlvey leave the fruit buds uninjured — 

 even those of the peach — at whatever time of the winter they are 

 applied. 



It is possible that their use may be still further cheapened by 

 experiments showing the precise amount necessary to produce the 

 full etlect — a point not covered by our work at Summerfield, where 

 both washes were used more freely, perhaps, than is neces- 

 sarv in practical work. 



