74 
samples may show that less than one percent of the kernels are 
actually injured. Corn in the ear may sometimes be sorted to 
advantage, if • infested, with a view to removing ears showing 
injury and shelling and bagging the remainder. A general infesta¬ 
tion may often be checked in its development by opening the ware¬ 
house in winter to lower the temperature, or by the use of heat 
as is presently to be described. 
If, however, it appears that an infestation is general and the 
injury considerable, and that simple measures will not be sufficient, 
some more general program will he necessary. If fumigation with 
either carbon bisulfid or hydrocyanic acid gas is practicable under the 
conditions, this is by all means the most effective and satisfactory 
process in such cases; but this requires that it shall be possible to 
make the granary or storeroom virtually gas-tight, or so tight that 
the leakage of gas will be so slow that a fatal atmosphere may be 
maintained for a period of several hours. 
Hydrocyanic acid gas is the more poisonous of these two sub¬ 
stances, but the more difficult and dangerous of application, and 
as it has comparatively little penetrating power, it can not be used 
against insects infesting grain in bulk or against those which are 
inclosed within the kernel. It is the best fumigant, however, for 
use against the Mediterranean flour-moth, and for any other soft- 
bodied insects which do not penetrate deeply into the grain. Car¬ 
bon bisulfid must be chosen if hydrocyanic acid gas is not available. 
Even where the storage rooms can not be made fit for the fumiga¬ 
tion process, it may be possible to accomplish the purpose by con¬ 
structing a special room or even erecting a small separate building 
thru which infested material may be passed in comparatively small 
lots. 
Next to fumigation, extremes of temperature, especially sudden 
changes from one extreme to another, are on the whole, the most 
effective. 
FUMIGATION WITH HYDROCYANIC ACID GAS 
Preliminary to the fumigation of a mill, warehouse, or granary, 
the room or rooms to be fumigated should be thoroly cleaned and 
the sweepings burned. This operation is particularly important, 
as the gas to be used has little penetrating power, and living in¬ 
sects nesting away in a pile of rubbish, or hidden in a crevice 
packed with dirt, may escape uninjured. Next, everything must 
be done to make the place tight, windows and doors receiving 
special attention. Cracks around window-frames should be tightly 
stuffed with cotton batting, macerated paper, or white waste, or 
else thick soft paper should be fastened over the cracks with car¬ 
penters’ glue or a good quality of flour paste. Broken or missing 
window-panes should, of course, be replaced. Keyholes in doors, 
and spaces between the door-frame and the door itself should be 
