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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
President E. C. Stackman: The papers are now open for discussion. 
Professor Wetzell: I have nothing to offer in the way of dis¬ 
cussion, but would like to state that I have very good reasons for believ¬ 
ing that the fireblight, Bacillus amylovorus is not a native of North 
America. I have considerable circumstantial evidence to prove that it 
is not. I hoped to have this ready for this meeting but have been 
unable to do so. 
Mr. R. Kent Beattie: Where does it come from? 
Professor Wetzell: I have reason to believe it is Asiatic. 
Adjournment, 12:30 p. m. 
Afternoon session , Saturday , December jo, 1922 
The meeting convened at 1:30 p. m., President Sanders presiding. 
President J. G. Sanders: The first paper will be presented by Mr. 
L. Haseman. 
AMOUNT OF ARSENIC PLACED IN CALYX CUPS AND 
LETHAL DOSAGE FOR APPLE WORM 
By L. Haseman, Columbia, Mo. 
Abstract 
The original purpose of this investigation was to determine what type of spray 
nozzle and what pressure places the greatest quantity of arsenic in the lower calyx 
cup of apple blossoms for the control of the codling moth, Carpocapsa pomonella. 
The spray tests are made immediately following the dropping of the petals by using 
usually three nozzles each w r ith three pressures. To determine the calyx content of 
arsenic a counted number of the small apples are collected from each of the test trees 
and the lower calyx cups with their arsenical content are carefully removed for chemic¬ 
al analysis. In this way it has been possible to determine the average arsenical content 
of the calyx cup of each apple from trees treated with different pressures and nozzles. 
These experiments show that a high pressure and coarse nozzle is less effective than 
a lower pressure with a nozzle throwing a finer mist. They also show that where the 
average calyx content of arsenic is the highest the percentage of calyx worms in picked 
apples is not always the lowest. 
After determining the average quantity of arsenic placed in the calyx cups under 
good orchard management, the investigation was enlarged in order to determine 
whether or not this quantity of arsenic is sufficient to poison apple worms attempting 
to enter at the calyx end of the fruit. This called for careful laboratory tests to de¬ 
termine the lethal dosage for apple worms. Doses of powdered arsenate of lead 
varying from one millionth to five ten thousandths of a gram were fed to apple worms 
of varying stages of development. To administer these small doses one or more 
drops of distilled water with the dose in suspension were placed on bits of apple 
