550 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
their eggs on the grain while it is in the field and the larvae attack the 
grain either before or after it is harvested, so that infested grain may be 
brought into the warehouse or mill. These insects attack or breed in the 
whole grain and are destroyed in the process of milling. 
After the grain is ground it may become infested with insects at any 
time during its further progress through the mill to the packing table. 
As practically all of the cereals are superheated before they are packed 
all stages of the insects, if any are present, are usually destroyed by this 
cooking or sterilization. Sometimes, however the sterilization is not 
complete and some of the insects may pass on to the packing table and be 
sealed up in the finished package. v 
In one mill we found that the corn meal that was coming from the 
sterilizer had only reached a temperature of 140°F. This is high enough 
to kill all insect life if this temperature could be maintained for two hours 
or more, but as the corn meal goes into the sterilizer cold, and as it takes 
it only four minutes to pass through, it is evident that such steriliza¬ 
tion is worse than useless, because it does little or no good and gives a 
false sense of security. When the steam pressure was raised from 22 lbs. 
to 30 lbs. the temperature of the corn meal as it came from the sterilizer 
was raised to 155° to 157° F. At 40 lbs. pressure the temperature of the 
meal was raised to 174°. 
Tests made in our laboratories showed that while most of the insects 
in germea and corn meal were killed when subjected to a temperature of 
180°F. for four minutes, a few beetles and a very few moth larvae sur¬ 
vived the ordeal. Our tests show that to be thoroughly effective the 
temperature must reach 200°F. if the time of exposure in the sterilizer 
is to be only four minutes. If the temperature is to reach only 180°F. 
this should be maintained for at least 8 or, better still, 10 minutes. 
After sterilization the cereal usually passes through a series of eleva¬ 
tors, over various belts and through screens and hoppers. During much 
of this time it is exposed to contamination by insects. Many of the 
elevators and hoppers are infested with larvae practically all of the time. 
Some of these may be carried with the supposedly sterilized cereal to the 
packing table and be sealed up in the packages. Or some of the moths 
that are flying about at night may lay a few or many eggs in some of the 
exposed places and when the mill starts up next morning there is every 
chance of these eggs being carried directly to the packages where they 
will be carefully and securely packed with the cereal. 
The following brief statement summarizes the results of some of the 
