130 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
The increased mortality among the weevils on treated plants pro¬ 
tected from dew and rain, as compared to the mortality on treated 
plants exposed to deposition of dew and rain is very marked. 
Day. 1234567 89 10. 
Chart 4.—Diagram showing total percentage of mortality among boll weevils on 
cotton plants treated with calcium arsenate: A, on plants protected from all dew 
and rain; B, on plants exposed to normal precipitation. Also natural mortality 
among weevils on non-treated plants: Ai, on plants protected from all dew and 
rain; Bi, on plants exposed to normal precipitation. 
Reference to Table II shows that, using lead arsenate, the mortality 
on protected plants was 85.6 per cent during 10 days and on exposed 
plants was 73.8 per cent. During the same period the natural mor¬ 
tality, as shown by the weevils on non-treated plants, was 14 per cent 
on plants protected from dew and 17.2 per cent on plants exposed to 
dew. The mortality creditable to the lead arsenate was therefore 
71.6 per cent in the case of the weevils on plants kept dry and 56.6 per 
cent on plants exposed to dew, or a mortality greater by 15 per cent 
on plants kept dry than that on plants receiving dew. 
