31 



ounce, by weight, of Paris green was stirred up in two and one 

 half gallons of water, — this quantitj^ being sufficient to give the 

 fluid a distinct green tint. 



The percentage of Paris green in the fluid was about twice the 

 strength ordinarily recommended for use in orchards by those who 

 claim to have tested the arsenical poisons for the codling moth. 



Two trees were treated, both of the same variety, and both hav- 

 ing checks likewise of that variety. The first of these trees was 

 first sprayed June 9, and the second June 13, no other difference 

 than this initial one of dates being made throughout the season. 

 Each was sprayed eight times, at intervals ranging from the 9th 

 June to the 3d September. The comparative results as shown by my 

 tables differ so little for these two trees, and for their checks, that 

 both couples may be considered as one. 



THE CODLING MOTH. 



A careful examination of a large number of apples on the treated 

 trees was made upon the 7th July, one month after the first poison- 

 ing. At this time we failed to find an apple on either of these 

 trees giving any evidence of injury by the codling moth, while the 

 check trees adjoining, so close that their branches touched, bore a 

 large number of infested apples. 



The first examination of fallen fruit was made July 16, five weeks 

 after the treatment of the first tree, and four and a half weeks after 

 that of the second. Both these trees had now been treated four 

 times in succession ; the first on the 9th and the second on the 13th 

 June, and both trees on the 20th and 30th June and on the loth 

 July. Of the 214 fallen apples from the poisoned trees, examined 

 July 16, only 16, or 7.9 per cent, were affected by the codling moth ; 

 while of the 570 apples examined from the check trees, which had 

 not been treated with Paris green, 58 per cent, had been so injured, 

 — more than seven times as large a ratio of these fallen apples hav- 

 ing been attacked by the codling moth on the check trees as on the 

 trees sprayed with Paris green. 



Tiie fact that in both cases the percentage of injury by the cod- 

 ling moth to the fallen apples was smaller at this time than at 

 any subsequent examination is sufficient evidence that the experi- 

 ment was begun early enough to meet the insect in the beginning 

 of its career. 



To exhibit more exactly the method of our work and the basis of 

 my conclusions, it may be worth while to follow through the history 

 of one of these trees to the end of the season, so far as injuries by 

 the codling moth and curculios are concerned. 



To get some idea of the condition of the fruit vpoii ihe tree, we 

 critically examined, July 21, 100 apples selected at random upon 

 each of the two contrasted trees, — the one poisoned with Paris 

 green and its check. Of the 100 apples upon the poisoned tree, 

 only two were infested by the codling moth, while of those upon 

 the check 33 had already been attacked. 



The second examination of fallen apples was made July 24, at 

 which time 177 were picked up from under the poisoned tree and 



