February, ’20] 
NEWELL: POISONING THE BOLL WEEVIL 
135 
with calcium arsenate at the same rate was found to contain from 10 
to 43.5 parts of arsenic per million. The dew was collected only from 
cotton leaves that showed a distinct, thorough white coating of the 
arsenates. 
3. Boll weevils deprived of all food and having dew from treated 
plants as the only source of moisture suffered a greater mortality than 
boll weevils confined on clear water, showing that the dew contained 
sufficient arsenic to produce death when the weevils were compelled 
to take the dew and no other food or water over a period of several 
days. However, such a condition does not occur in cotton fields. 
4. When boll weevils had access to food in the form of non-poisoned 
cotton squares and, at the same time, to dew from treated plants, no 
mortality resulted, showing that the weevil can be poisoned under 
normal conditions only by poisoning its food. 
Conclusions 
1. As the boll weevil is poisoned largely or entirely through taking 
poison with its food, machinery for applying poison to the cotton 
plants should be so designed as to apply the poison primarily to the 
squares, bolls and terminal buds, rather than to the foliage. 
2. The greatest mortality among the boll weevils occurred on the 
third day following application of the arsenates and fell off rapidly 
after the seventh day indicating that, other things being equal, appli¬ 
cations should be at intervals of a week, or less, apart. 
President W. C. O’Kane: Do you wish to discuss this paper? 
Mr. E. G. Kelly: Did calcium arsenate burn the tender foliage? 
Mr. Wilmon Newell: I am not able to answer this question 
positively. In our experiments, it did not. 
Mr. W. D. Pierce: I would call attention to the fact that in all 
of Mr. Newell’s experiments, lead arsenate proved more effective than 
calcium arsenate. I would like to ask him as to the method of appli¬ 
cation that he found the most successful. 
Mr. Wilmon Newell: In the case of both lead and calcium the 
highest efficiency was the method of application that forced the poison 
directly on the plants, as compared with distributing it in the form of 
dust clouds and allowing them to settle. 
Mr. R. N. Chapman: I would like to ask how large numbers 
those percentages of mortality are based on. 
Mr. Wilmon Newell: In the first table, in the protected cages, 
there were 250 weevils, and in the cages exposed to the rain and dew, 
there were 500 weevils. 
Mr. R. N. Chapman: Do you think there would be any'advan- 
