302 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
No. 9 they are more or less protected from later infestation by the 
common bean weevil. It also seems that of the four substances enum¬ 
erated ground burned lime (CaO) and Milltown Ball Clay No. 9 are most 
effective and give, at certain dilutions, perfect protection. Unfortunate¬ 
ly, ground burned lime causes the seed to crack and fortunately Milltown 
Ball Clay No. 9 leaves the bean in an apparently perfect physical 
condition. 
The data submitted in tables 3, 4, 5, and 6 indicate that Milltown 
Ball Clay No. 9, when mixed with common white beans, at the rate of 
one to ten will afford apparently perfect protection from later common 
bean weevil attack and, when mixed with shelled corn or wheat at the 
rate of at least one to fifty, will afford apparently perfect protection 
against subsequent angoumois grain moth attack. Most surprising of 
all, the data in tables 2 and 6 indicates that even when not in direct 
contact with the insect the clay is capable of exerting a reduction of 
infestation. 
Relative Humidity 
Prevention of common bean weevil attack on common white beans 
in storage by the maintenance of a low relative humidity, as set forth 
by Headlee, 4 when connected with Chambers’ and Metcalf’s experience, 
seem to indicate that the dusts tried at that time were acting through 
the maintenance of a low relative humidity, but when it was found 5 
that the hygroscopic power of calcium hydroxide and Milltown Ball 
Clay No. 9 was extremely low and at the same time that they were 
effective insecticides against the common bean weevil, that idea had to 
be deserted. 
Chemical Composition, Acidity and Alkalinity 
An effort was then made to determine whether chemical composition, 
acidity or alkalinity had anything to do with protecting common white 
beans from infestation by the common bean weevil. All materials 
were ground to the same fineness (200 mesh). Four different kinds of 
material were used. Their composition, pH value and organic content 
are set forth in the following table:— 
4 Headlee, Thomas J. Journal of Econ, Ent. vol. 10 p. 34-37. 
5 Headlee, Thomas J. Report of N. J. Agr. Exp. Sta., year ending June 1921 p. 
370-371. 
