21 
EXPERIMENTS WITH THE ARSENICAL POISONS FOR THE 
PLUM AND PEACH CURCULIO. 
(Conotrachelus nenuphar , Hbst.) 
The object of the following experiments was to ascertain some 
details of the food and feeding habits of the curculio and to 
jest its sensibility to arsenical poisons when distributed on the 
)rees which the insect frequents. In the case of the peach it 
was important also to find what amount of these poisons the 
eaves 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 
containing eggs, others not. July 2, fresh lot of beetles impris¬ 
oned 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 
lead vegetation, as shown by the absence of clilorophyl and 
bhe presence 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, 
bhe blossoms being, however, evidently preferred. Both calyx 
and corolla were perforated with small round holes, and eaten 
away from the edge. 
Three specimens taken in Southern Illinois were dissected April 
23 and found to contain vegetable tissues, chiefly of leaves (as 
shown by the fragments of spiral vessels), without fungi, and 
with more or less chlorophyl. Vegetable hairs and peculiar 
pollen grains, not those of fruit blossoms, were also recognized. 
Thinking it possible that the curculio might feed on flowers 
somewhat indiscriminately, we put a number under a bell glass 
with roses in full bloom. The next day, May 19, the petals 
were much eaten, and two days later calyx peduncles had 
