7 



AESENICAL POISONS FOE THE CODLING MOTH. 



( Carpocapsa pomonella, L. ) 



Order Lepidoptera. Family Tortricid.e. 



I published last year (1885), in the Report of the State Department 

 of Agriculture* and in the Transactions of the State Horticultural 

 Society,! a report on some preliminary experiments made with 

 two arsenical poisons and with lime, for the codling moth and the 

 curculios, the general result of these experiments going to show 

 that about two thirds of the apples subject to loss through the 

 codling moth, and one half of those liable to be destroyed by the 

 curculios, might be saved by spraying eight times with Paris 

 green. Last year was, however, an exceptional year, the apple 

 crop being very unusually light, following a good crop of the year 

 before. Moreover, eight times' spraying was clearly an excessive use 

 of the poison, the arsenical compounds being presumably ineffective 

 against the second brood of the codling moth, and certainly dan- 

 gerous to health, if not to life, if used on the apple after mid- 

 summer. Our work of last season was consequently inconclusive 

 with respect to some important points; and I made this summer 

 (1886) similar experiments on a larger scale, intended to com- 

 plete and test the evidence of the year before, to try arsenic in 

 solution in comparison with London purple and Paris green, and 

 especially to test carefully and thoroughly the effect of a moderate 

 number of sprayings with poisonous insecticides applied only so 

 early in the season that there could be no possible question of 

 danger to the consumer of the fruit. I used this year Paris green 

 and a solution of arsenic in comparison on eight selected trees. 

 Two of these were sprayed with a solution of white arl^nic and 

 six with Paris green in water — two of the six sprayed once. May 

 11; two twice. May 11 and 24; and tw^o three times — the last, June 

 6. Companion trees were selected as checks upon each of those 

 thus treated, the check trees being, of course, left unpoisoned. 



The Paris green mixture was the same as last year, three 

 fourths of an ounce by weight, of a strength to contain 15.4 per 

 cent, of metallic arsenic, being simply stirred up in two and a 



♦Appendix, pp. -26—45. 

 tVol. xix, pp. 10.3—124. 



