Tue CoNnFuSED FLouR BEETLE 91 
means that sifting will remove the beetles from only the higher grade 
flours. It also indicates that in the process of milling eggs or young 
larvae might be included in the coarser and lower grade flours while 
they might be excluded from the finer, high grade flours. 
For small amounts of flour the safest and simplest method is to 
heat it in the oven. This may be done by placing the flour or cereal a 
little less than two inches deep in pans and keeping the fire as low as it 
will burn well until the surface of the cereal reaches a temperature 
of 85°C (185°F). If a gas, gasoline, or kerosene stove is used, the 
fire should be turned out and the oven left closed for thirty minutes 
after the above temperature has been reached. If a wood or coal stove 
is used, the oven door should be left open and the fire kept as low 
as possible during the thirty minutes after obtaining the desired 
temperature. It is necessary that the fire should be kept low in order to 
allow as much time as possible for the heat to penetrate to the center 
of the cereal before the top or bottom of the cereal reaches a tempera- 
ture which will injure it. It has been stated that some materials will be 
injured if heated to 96°C. 
Stirring the material when it has reached 85°C helps to distribute 
the heat. Figure 15 shows the curves for the temperatures of the top, 
bottom, and center of a pan of cereal heated as described above. It will 
be noticed that it required fifteen minutes for the top of the cereal to 
reach a temperature of 85°C. The temperature of the bottom of the 
cereal follows that of the top, while the temperature of the center lags 
behind. But even the temperature of the center passes well above the 
fatal temperature for the beetles, which is about 48°C. At the same 
time the top of the cereal does not reach the temperature which will in- 
pure it. 
When the heat treatment is followed by careful storing in tight, 
clean containers, the possibility of loss due to Tribolium confusum is 
eliminated. The heating of all cereals as soon as they are brought into 
the house, in warm weather, is strongly recommended. Eggs or small 
larvae may be present in the cereal when a close search fails to reveal 
them, and a little time spent in heating the cereal will eliminate the 
danger of infesting the home. It is much easier to keep the beetles 
out than it is to get them out if they once get in. 
If a suitable thermometer is not at hand, a heat testing wax is 
on the market which is standardized to melt at the proper temperature. 
If the grocer does not have the wax he may get it from his wholesale 
dealer. A box of the wax costs only five cents and contains nearly a 
year’s supply. 
