SOCIETY OF CENTRAL ILLINOIS. 251 



effects of the poison were somewhat apparent on both branches, 

 reddish discolorations occurring where the fluid had gathered in 

 drops, and also along the margins of the younger leaves. Further 

 rains occurred on the 16th and 17th. On the 18th, the discolored 

 spots had increased in size, those on the branch sprayed with the 

 stronger solution being somewhat larger and more numerous. No 

 leaves had fallen, but those worst affected were easily detached, 

 and doubtless would have fallen eventually. This loosening of 

 the leaves was evidently due, not to damage to the petiole, but to 

 premature ripening of the leaf, * consequent on the chemical 

 injury to the blade. June 8, two other branches were sprayed as 

 before, substituting Paris Green for London Purple in both 

 mixtures. Light rain followed the same day, and more on the 

 9th. On the 10th a scorching of the leaves was somewhat 

 evident, a little more so where the stronger mixture was used, 

 while on the 18th the condition of the foliage was practically the 

 same as on those branches treated with London Purple — if any- 

 thing, a little less severely injured. There was also a barely per- 

 ceptible difference in favor of the weaker mixture. Supposing 

 that all the worst injured leaves were rendered practically useless 

 to the tree, the loss of foliage would probably amount to four or 

 five per cent. 



There can certainly be no further question of the liability of 

 the curculio to poisoning by very moderate amounts of either 

 London Purple or Paris Green while feeding on the leaves and 

 fruit of peach or plum; but much additional experiment is 

 needed to test the possibility of preventing serious injury to these 

 fruits by this means. The pupal hibernation and late appearance 

 of a considerable per centage of, the curculios make it possible 

 that sprayings must be several times repeated, and perhaps car- 

 ried further into the season than is consistent with safety ; and 

 the limit of tolerance of these poisons by the peach under ordi- 

 narily trying circumstances has not been clearly ascertained. 

 Further, the observations above reported on the food plants of the 

 curculio make it likely that, in nature, a smaller proportion of 

 the food of these beetles comes from the peach or the plum than 

 has hitherto seemed probable, and that poisons there applied 

 would kill less certainly. It seems worth while to make the 

 attempt to attract the adult to flowering plants in the orchard 

 other than the peach, with the hope of poisoning it there 

 (especially late in the season) without using these dangeious 

 insecticides on fruits afterwards to be eaten. 



DISCUSSION. 



Dr. Schroeder— I am afraid that there may be danger to the 

 land, connected with the use of arsenical poisons. Is it not pos- 



♦Ascertained by studying sections of the petiole. 



