February, ’20] 
NEWELL: POISONING THE BOLL WEEVIL 
125 
arsenate and others with lead arsenate, using approximately ten pounds 
of the poison per acre. Cages were then placed over individual treated 
plants (see fig. 1), each cage floored with paper as tightly as possible 
and fly paper placed around the outside lower edges of the cage to 
exclude ants and a counted number of field-collected boll weevils intro¬ 
duced into each cage. Certain cages were covered at night and dur¬ 
ing showers with a heavy oilcloth cover, extending to within 12 inches 
of the ground (see fig. 2) so that the plants were protected against all 
deposition of visible moisture. Other cages, paired with these in the 
experiments, were not supplied with covers and the plants in them 
received the same precipitation of dew and rain as plants under normal 
field conditions, except that covers were placed on them when severe 
storms occurred in order to prevent excessive washing off of the poison 
or possible drowning of the weevils. 
Corresponding cages, both “covered’’ and “uncovered/’ were placed 
over non-poisoned plants to serve as checks. Observations were made 
twice daily in all cages to determine the mortality among the weevils. 
The following table, showing the results obtained in two series of 
experiments, using lead arsenate and calcium arsenate on both cov¬ 
ered and uncovered plants, is typical of the observations made on the 
total of 2,250 weevils used in the field experiments. 
Table I. Mortality Among Boll Weevils on Plants Protected from Dewand Rain (“Cov¬ 
ered”) and on Plants Exposed to Dew and Rain (“Exposed”). Fifty Weevils per Plant, 
One Plant per Cage. Six Cages. Poison Applied 7 p. m., September 16, by Direct Appli¬ 
cation with Dust Sprayer (“Blast Method”) at About 10 Pounds per Acre. 
Date 
Number weevils dead each day 
Check 
(“natural mortality”) 
Treated with lead 
arsenate 
Treated with calcium 
arsenate 
Sept. 
Covered* 
(Ser. 1) 
(50 weevils) 
Exposedf 
(Ser. 11) 
(50 weevils) 
Covered* 
(Ser. 1) 
(50 weevils) 
Exposedf 
(Ser. 11) 
(50 weevils) 
Covered* 
(Ser. 1) 
(50 weevils) 
Exposedf 
(Ser. 11) 
(50 weevils) 
17. 
3 
2 
3 
0 
0 
0 
18. 
4 
5 
4 
6 
0 
0 
19. 
13 
11 
17 
9 
1 
0 
20. 
11 
11 
8 
6 
0 
0 
21. 
4 
3 
2 
2 
0 
0 
22. 
.... 6 
3 
4 
3 
0 
0 
23. 
4 
4 
4 
3 
1 
0 
24. 
2 
2 
0 
3 
0 
0 
25. 
1 
2 
2 
0 
1 
4 
Totals. 
48 
43 
44 
32 
3 
4 
Weevils alive at end of 
exp..•. 
2 
2 
1 
4 
28 
38 
Missing. 
0 
5 
5 
14 
19 
8 
* No visible moisture on plants at any time during experiment. 
t Heavy dew on plants on Sept. 17, 24 and 25; medium dew on 19th, 20th, 21st, 22nd and 23rd and 
light dew on 18th. 
