February, ’18] wilson and gentner: cabbage worm 
81 
the Agricultural Chemistry Department of the University. The plats 
from which these heads were taken had received five sprayings, the last 
spray having been applied about a week before picking. In preparing 
the heads for analysis, only the outer leaves were removed as is done 
by the grower, then one more layer of leaves was removed to correspond 
to those taken off by the housewife. Not even a trace of arsenic was 
secured in the analyses. 
Inquiries have been made with regard to feeding the outer leaves to 
stock, therefore an analysis was made of the outer leaves of three plants, 
two taken from the plats sprayed five times with lead arsenate and 
Paris green respectively and one sprayed twice with calcium arsenate. 
The results of the analysis were as follows: 
Plant sprayed with lead arsenate. 56.7 mgms. AS2O3 
Plant sprayed with Paris green. 22.8 mgms. AS2O3 
Plant sprayed with calcium arsenate. 1.25 mgms. AS2O3 
These are large quantities of arsenic and would undoubtedly poison 
stock. The fatal dose of arsenic for mature man varies from 8 to 20 
mgms. 
Conclusions: While Paris green gives efficient control the cost is 
too high for economical use. Lead arsenate and calcium arsenate at 
the rate of one pound of the powder or two pounds of the paste to fifty 
gallons, with the addition of one pound or more of common laundry 
soap, give efficient control and are the most economical to use. 
The failure of zinc arsenite to control the cabbage worm is not under¬ 
stood and further experiments will be made. 
No trace of arsenic was found to be present on sprayed heads pre¬ 
pared for cooking even when sprayed as late as a week before picking. 
The outer leaves may carry enough arsenic to poison stock and are 
therefore dangerous to use for that purpose. 
President It. A. Cooley: Do you wish to ask any questions of 
Mr. Gentner, or discuss his paper? If not, the next paper is, “ Poi¬ 
soned Bait Experiments with the Onion Maggot,” by Mr. Neale F. 
Howard, Madison, Wis. 
7 
