Tue ConFuSsED FLourR BEETLE 81 
flaky material which is chosen by the beetles. But when cornmeal was 
introduced no choice for it was indicated. Unfortunately the experi- 
ments in which the cornmeal was included were not properly checked 
and will not be included here. 
Since the above experiments seemed to indicate that coarseness 
was a factor in invasion, an experiment was tried in which the foods 
differed in respect to this factor, but were of the same nutritive value. 
The bran was sifted and that which was retained by a No. 2 bolting 
cloth was divided into two portions, one which was left in the original 
coarse condition, and the other which was ground until it would pass 
through a No. 5 bolting cloth. The fine material was placed in one 
half of a container and the coarse material in the other half while the 
beetles were placed in a depression in the center, as in the previous ex- 
periments. An average of 62 per cent of the beetles was found in the 
coarse material. 
For a further check on the factor of coarseness, an experiment 
was planned to exclude the factor of nutrition. For this purpose pine 
sawdust, which had been treated with alcohol to dissolve out the oils, 
was employed. A coarse grade, which passed through a No. 0000 
bolting cloth but which was retained over a No. 00 cloth was placed in 
one fifth of the jar and the other four fifths of the jar contained fine 
sawdust which passed through a No. 2 bolting cloth. The experiments 
were manipulated in the same manner as when the five grades of wheat 
flour were used. The results were surprisingly like those obtained with 
the wheat flours. 
First Second Third 
Material count count count 
Fine sawdust No.1 .... 25 11 10 
Fine sawdust No.2 .... 28 8 5 
Fine sawdust No.3 .... 11 13 12 
Fine sawdust No. 4 .... 2 20 23 
(C@girse Sainyalotse .oocdec 34 48 49 
These results make it evident that the coarseness of the flour or 
cereal may be the dominant factor concerned in invasion by insects. 
The fact that similar results were not obtained with cornmeal makes 
it seem evident that this factor is concerned with the tactile responses 
of the beetles. The beetles respond to the flaky materials between 
which they can penetrate very readily while the more granular material 
does not offer the same stimulus, because the finer particles fill in the 
spaces between the larger particles and thus offer much less favorable 
opportunities for the beetles to enter the material. 
