132 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
tive analysis. The following table shows the number of parts of 
arsenic per million in the dew as determined by Mr. Collison. Each 
sample of dew analyzed was collected from leaves well covered with 
poison from several dozen plants in different parts of the treated plat 
and the arsenic content may, therefore, be considered as decidedly 
above the average arsenic content of dew on treated plants. 
From plants treated with 
Dew collected 
Parts arsenic 
per million 
Lead arsenate 
First morning after application 
6.7 
Lead arsenate 
Second morning after application 
6.7 
Calcium arsenate 
First morning after application 
43.5 
Calcium arsenate 
Second morning after application 
10.00 
From the foregoing it is seen that the actual amount of arsenic in 
the dew from treated plants is remarkably small, even when collected 
from leaves heavily coated with the arsenate, and presumably a weevil 
would have to consume very considerable amounts of it in order for 
it to prove fatal. Experiments were accordingly made to determine 
whether such dew would prove fatal to boll weevils when all other 
sources of moisture were eliminated. 
Large battery jars were prepared, each jar having a layer of dry 
sand in the bottom and the top covered with cheesecloth to permit 
circulation of air. A counted number of field-collected weevils was 
introduced into each jar and thereafter supplied with dew, collected 
from the treated plants the morning following the application of poison, 
by placing the dew in shallow tin trays. No other water was supplied 
and the weevils had no food. Corresponding lots of field-collected 
weevils were kept in similar jars, but supplied with clear water instead 
of dew and the daily mortality noted. Under these conditions the 
weevils went rather frequently to the dew in the trays and remained 
with their beaks inserted in the dew for periods varying from lj to 5 
minutes, 2\ minutes being about the average. It is assumed that 
they were drinking during these periods. 
The mortality, during 10 days, among 80 weevils supplied only 
with dew from lead-arsenate treated plants was 80 per cent, among 
80 with dew from calcium-arsenate treated plants was 68.7 per cent 
and among 80 with clear water was 43.7 per cent; all of which is 
shown in the following chart: 
In the course of these experiments one weevil lived for 12 days on 
.an exclusive diet of dew from calcium-arsenate treated plants and 
