1114 
Journal of Agricultural Research 
Vol. XXVIII, No. 11 
Table VI.— Percentage of wheat kernels infested and number of adult insects found 
free in ounce samples in bin the wheat of which registered 58° F. at surface, 104° F. 
6 inches below surface, 109 0 F. 2 feet below surface, and 88° F. at bottom of bin 
about 4 feel below surface 
Location of probe 
Depth at which 
sample was 
taken 
At end of bin 
At center of bin 
At end of bin 
Per 
cent 
of ker¬ 
nels 
in¬ 
fested 
Number of 
mens of- 
speci- 
Per 
cent 
of in¬ 
fested 
ker 
nels 
Number of 
mens of- 
speci- 
Per 
cent 
of ker¬ 
nels 
in¬ 
fested 
Number of 
mens of- 
speci- 
Oryza 
Pusil- 
lus 
Para¬ 
sites 
Oryza 
Pusil- 
lus 
Para¬ 
sites 
Oryza 
Pusil- 
lus 
Para¬ 
sites 
6 inches_ 
92.1 
2 
6 
3 
93.2 
2 
4 
2 
88.9 
6 
3 
’ 2 
12 inches_ 
94.3 
27 
12 
0 
94 
7 
14 
8 
93.9 
7 
7 
3 
18 inches_ 
90.9 
/ 
12 
3 
96.4 
7 
15 
3 
90 
6 
8 
3 
24 inches_ 
92.3 
3 
17 
13 
93.7 
4 
4 
6 
96.5 
3 
3 
0 
30 inches_ 
91.8 
4 
9 
3 
91.2 
4 
3 
3 
92.3 
3 
5 
0 
36 inches_ 
93.4 
3 
5 
1 
90 
1 
4 
2 
84.2 
3 
3 
6 
42 inches_ 
95. 5 
24 
6 
6 
91.4 
2 
10 
2 
89.8 
4 
10 
9 
48 inches_ 
90 
4 
1 
0 
91.1 
1 
7 
2 
94.9 
32 
14 
9 
DESTRUCTION OF HEAT BY FUMIGATION OF MOST PRACTICAL 
VALUE 
Whatever may be the reader’s conclusion regarding the actual cause of heating 
in insect-infested seeds, there can be no doubt as to the value of any treatment 
that will reduce the temperature of the seeds to normal. The placing of heating 
seeds in cold storage will not prevent insect activity if the seeds are sacked or 
placed in bulk and are already heating when placed in cold storage. Cowpeas 
infested with Bruchus quadrimaculatus and beans infested with Bruchus obtectus 
continued to heat for several months when placed in cold storage at 32° F., 
according to the experience of several operators of storage plants. 
In ordinary storage where seeds are stacked as indicated in figure 2, the heating 
seeds radiate sufficient heat to raise the temperature appreciably in the spaces 
between the sacks. Thus, with a warehouse temperature of 58° F. the space 
between sacks No. 22, 23, and 24 (sacks with temperatures of 88°, 100°, and 
92° F., respectively) registered 78° F. In many instances the temperature in 
the spaces between or touching heating sacks was raised to 70° and 72° F. 
Bruchids at 58° F. are not capable of mating or spreading, but at temperatures 
above 70° F. they reproduce actively and bring about a spreading of the infesta¬ 
tion at a season of the year when the owner normally expects protection from 
insects due to the action of cold weather. The same holds true in wheat bins on 
the farm, even in bins of wheat where the seeds are not deeper than 1 to 2 feet. 
The heating permits feeding and reproduction to progress even in the dead of 
winter. A thorough fumigation with hydrocyanic-acid gas or carbon disulphid 
kills the insects or a sufficient number of them so that those that remain can not 
maintain a condition favorable to the production of progressive destruction. 
SUMMARY 
It is well known that the heating of grain may be caused by a high moisture 
content. Spontaneous heating in damp grain is occasioned by the biological 
oxidation of dextrose and similar sugars, chiefly in the germ or embryo of the 
kernel. Enzymatic action and growth of molds have been said to be associated 
with increasing temperatures when no insects are present. With heating due 
to causes other than insect infestation this paper does not deal. 
It has been assumed by certain grain authorities that when wheat shows a 
moisture content of less than 14.5 per cent it is likely to remain in condition if 
