134 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
Mortality Among Weevils Supplied with Food and with Dew 
from Treated Plants 
Field-collected weevils were confined in battery jars as described 
in the preceding experiments, furnished with dew from treated plants 
in the same manner and in addition given fresh cotton squares each 
morning. They, therefore, had cotton squares as a source of both 
food and moisture, as is the case in the field, and in addition had dew 
constantly available for drinking purposes. The mortality, during 10 
days, among 80 weevils confined with dew from lead-arsenate treated 
plants, 80 confined with dew from calcium-arsenate treated plants 
and 80 confined with clear water is shown in the following table. 
Table IV. Daily Mortality Among Boll Weevils Supplied with Food and with Dew from 
Poisoned Cotton Plants 
Liquid 
Number 
weevils 
confined 
Daily mortality 
Total dead 
during 
10 days 
Per cent mor¬ 
tality during 
10 days 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
Dew from lead-arsenate treated 
plants. 
80 
0 
0 
0 
0 
0 
1 
2 
0 
2 
1 
6 
7.5 
Dew from calcium-arsenate 
treated plants. 
80 
1 
0 
0 
0 
0 
1 
0 
1 
1 
1 
5 
6.2 
Water (“check”). 
80 
0 
0 
0 
0 
1 
0 
1 
1 
5 
0 
8 
10.0 
As the mortality among the weevils having access to water was fully 
as great as that among those having access to the poisoned dew it is 
at once evident that either the weevils did not partake of the dew or 
they did not drink enough of it to cause any mortality. It is to be 
remembered, in this connection, that the dew to which these weevils 
had access was collected the first morning following the application 
of arsenates and only from leaves which showed a relatively heavy 
coating of the poison. 
Summary 
1. The mortality among boll weevils on cotton plants treated with 
lead and calcium arsenates and kept protected from all rain and dew 
was appreciably higher than the mortality on plants similarly treated 
but exposed to dew and normal precipitation. As the presence of dew 
or rain water on the cotton plants does not increase the effectiveness 
of either lead or calcium arsenate as a boll weevil poison it is evident 
that mortality from the use of either of these poisons is brought about 
by ingestion of the poison with the weevil’s food and not by drinking 
the so-called “ poisoned dew.” 
2. Dew collected from cotton plants treated with lead arsenate at 
the rate of approximately 8 pounds per acre was found, upon analysis, 
to contain 6.7 parts of arsenic per million. Dew from plants treated 
