SOCIETY OF CENTRAL ILLINOIS. 247 



over the entire tree, from the main trunk to the smaller twigs, 

 makes it probably impossible to reach it by washes or to dislodge 

 it by hand, or, indeed, to save a tree which is once infested by it. 

 Prompt destruction of all such trees, so as to destroy the insect 

 with them, seems the only measure worth discussing Unques- 

 tionably, whatever the details of the life history may prove to be, 

 infested trees cut up and burned in winter will contain the beetle 

 in some one or more of its stages. 



ARSENICAL POISONS FOR THE PLUM AND PEACH CURCULIO. 



The following report of results of my recent experimental work 

 on the common peach curculio is intended to correct and com- 

 plete a reporter's summary of remarks made in August, 1888, at 

 a meeting of the Central Illinois Horticultural Society, at Cham- 

 paign, as republished in the last report of the U. S. Entomolo- 

 gist, page 75. The experiments there alluded to were not gen- 

 eralized by me, but were described as merely preliminary to 

 a much more elaborate series which I have since carried 

 through. 



The object of these experiments has been to ascertain some 

 details of the food and feeding habits of the curculio. and to test 

 its sensibility to arsenic poisons when distributed on the trees 

 which the insect frequents. In the case of the peach, it was im- 

 portant also to find what amount of these poisons the leaves, 

 might receive without marked injury. 



FEEDING EXPERIMENTS. 



June 15, 1888, plum curculios confined with plum leaves, 

 June 16, one observed making a deep, sharp, oblong excavation 

 in the midrib; similar work on other midribs, petioles and stems. 

 Beetles, also seen gnawing the surfaces of the leaves, especially 

 the fresher terminal ones. Leaves removed, and green plums- 

 substituted. June 19, plums peppered with holes, some contain- 

 ing eggs, others not. July 2, fresh lot of beetles imprisoned 

 with both leaves and green plums. The next day both had been 

 eaten, the plums perhaps the more freely. 



Several examples taken April 14, 1889, before peach trees were 

 in bloom, were proven by dissection to have last fed on dead 

 vegetation, as shown by the absence of chlorophyl and the pres- 

 ence of some of the fungi of decomposition. Curculios confined 

 April 19, with both dead and living peach leaves, fed only on the 

 latter, not having touched the dead leaves at the end of 

 three days. Peach blossoms being placed in the cage, with fresh 

 leaves also, April 22, both were freely eaten at once, the blos- 

 soms being, however, evidently preferred. Both calyx and 



