Appendix. 



163 



If. regardless of this difference, we take tiiese twenty trees as a group, 

 we find that forty-eight per cent of the young scales of the preceding 

 year were dead when the experiment began; and that forty-three per 

 cent of these were killed by the second day after treatment, sixty per cent 

 by the third, eighty-four per cent by the firth, and eighty-six per cent by 

 the sixth. The average effect of the insecticide, as shown by counts 

 made from the seventh to the twenty-second day, amounted to eighty- 

 eight and four-tenths per cent; or, if we include only the counts from 

 the tenth to the twenty-second day, it stands at eighty-nine per cent. 



Lot hi. Sprayed with Lime, Sulphur, and Blue Vitriol, March 3. 



Third Lot of Trees. Oregon Wash. 



This lot of experimental trees corresponds to the first in all particulars 

 except that the Oregon wash of lime, sulphur, and blue vitriol was used 

 as an insecticide instead of the California wash, and that the experiment 

 was made with seven trees instead of nine. The variations in treatment 

 omitted in this lot correspond to those of Nos. 5 and 7 of Lot 1. All 

 were apple trees, growing in the same orchard as those of the first lot. 



Tree No. 11. — An eighteen-foot tree, with an eight-inch trunk and a 

 twelve-foot spread; in excellent condition, and moderately infested. 

 Sprayed with fifteen gallons of water daily for seven days, beginning 

 March 4, the next day after insecticide treatment. Sixty-seven per cent 

 of the scales alive at the beginning of the experiment; eighty-five per 



