STATE POilOLOGICAL SOCIETY. 161 



The benefit to the picked fruit apparent from a single spraying, 

 stands at forty-seven per cent, and that from twice spraying, at 

 ninety per cent, while that from thrice spraying falls away, again, 

 to seventy-seven per cent. Or, summarizing still more briefly, we 

 may sa}', in general, that the results of once or twice spraying with 

 Paris green, in early spring, before the young apples had drooped 

 upon their stems, resulted in a saving of about seventy-five per cent of 

 the ajjples exposed to injury by the codling moth. 



I wish especially to emphasize the fact that the results now ob- 

 tained are drawn from computations so made that the}' ma}- be ex- 

 pected to hold good without reference to conditions other than 

 variations in the treatment itself. The apples protected from in- 

 jury by the codling moth are evidently apples effectively j^oisoned, and 

 our "ratios of benefit" really express the ratios of these poisoned 

 apples to the whole number treated. These ratios clearly will not 

 vary either with the abundance of the apples, with the abundance 

 of the codling moths, or with anything else except the original 

 treatment, and subsequent accidents affectiug the length of time dur- 

 ing which the poison may adhere to the apple. This view is, in fact, 

 substantiated by the essential agreement between the results of 1885 

 and 1886, under conditions as widely difl^erent as it would be pos- 

 sible to find by ten years' waiting. 



We have next to determine the time of the year at which poison- 

 ing is the most effective : whether, in fact, it takes principal effect 

 upon the first brood or the later ones. A moment's reflection will 

 show that if only the first brood of the larvae was directly di- 

 minished in a certain ratio, the second brood should show a similarly 

 diminished ratio, since these descend from the first ; whereas if both 

 first and second broods are directly poisoned, then the ratio of dam- 

 age to the second brood should be greater than that to the first ; or, 

 in other words, the percentage of benefit to the picked apples should 

 be greater than that to the fallen. Our data for the present season 

 do not apply to this question, since all the sprayings were made in 

 May and early June while the apples were still very small ; and it 

 is incredible that the poison should have remained upon the fruit 

 through all the vicissitudes of weather and time for the two months 

 and more that elapsed before the appearance of the second brood of 

 larvae. The results of 1885, however, when the spraying was 

 continued until September 3, give us important information. Refer- 



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