184 THE PLUM CURCULIO. 
against the codling moth and curculio, more care would be required in resisting the 
attack of the latter. This season we arranged our experiments with this point directly 
in view. On June 4, the trees, both plum and cherry, were jarred and curculio were 
caught. The mark of the curculio was also found on both cherries and plums. The 
trees were sprayed June 6, June 12, and June 20. The material was the same as that 
used in spraying the apples, namely, 1 pound London purple to 100 gallons water. 
Careful examinations June 12 found no stung cherries and very few plums. June 26, 
250 cherries were picked from the sprayed trees, and not one was injured. The crop 
of cherries was large and no cherries from the sprayed trees were wormy. July 16 and 
18 the fallen plums were all gathered under the trees and cut open. On tree No. 1 
there were 16 plums, of which 10 were wormy. Tree No. 2 (wild goose), 117 plums, 
23 wormy. ‘Tree No. 3 (Washington), 33 plums, 3 wormy. Close examination found 
no stung plums on the trees, and the crop upon picking was very free from injury. 
Cherry and apple trees near by not sprayed suffered seriously. 
CONCLUSIONS. 
From these experiments and those of former years I conclude that while one appli- 
cation will not save our plums and cherries and prevent apples from being stung, 
two or three applications may be of signal advantage. 
In 1888 Prof. Forbes began a series of observations to determine 
some details of the food and feeding habits of the curculio and to test 
its susceptibility to arsenical poisons when distributed on the trees 
frequented. Observations were also made on a strength of poison 
which might be used on peach foliage without marked injury. As a 
result of his studies he concluded: 
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 and plum, but much additional experimentation 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 percentage of the cur- 
culios make it possible that spraying 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 ordinarily trying circumstances had not been clearly 
ascertained. Further, the observations reported above on the food plants of the cur- 
culio make it likely that in nature a smaller proportion of the food of these beetles 
comes from the peach or plum than has hitherto seemed possible, 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 dangerous 
insecticides on fruits afterwards to be eaten. 
Prof. C. P. Gillette, in Bulletin 9 of the Iowa Agricultural Experi- 
ment Station, issued in May, 1890, records observations on the cur- 
culio and plum gouger, giving results of spraying plums with London 
purple for the control of both of these insects. His work led him to 
believe as follows regarding the efficiency of arsenicals: 
The two applications of London purple and water, although not made at the times 
best suited to destroy the curculio, apparently gave a protection of 44 per cent against 
the ravages of this insect. 
