June i4 ,1924 Effect of Fumigation 1109 
grain was due to the conversion by the insect at the time of transformation of a 
“certain amount of so-called ‘latent heat’ into sensible heat.” In other words, 
that a certain amount of “heat energy” is expended in the operation. This 
seems especially probable owing to the more or less complete histolysis during 
the pupa stage. Dr. C. L. Marlatt (7), present at the meeting, was of the 
opinion that the heat was partly produced by fermentation. Austin (7) said 
that he thought the heat due to the chemical action of the forces setting up the 
fermentation with the grain, while Dr. E, A. Schwarz said (7) that the accumu¬ 
lation in numbers of insects produced considerable heat, and referred to the 
hibernation in crowds of Megilla maculata. 
The heat produced by the honeybee cluster in winter has been well studied by 
Phillips and Demuth (11), who state that as the temperature of the air in the 
hive falls in winter the bees become less active until a certain critical temper¬ 
ature (about 57.2° F.) is reached, at which the bees undertake by muscular 
activity, not unlike that of shivering, to produce heat in order to keep warm. 
By such action the honeybees are able to maintain a temperature within their 
cluster of 86° to 95° F., when the outside temperature is 32° F. 
The writers have been told by owmers of grain elevators that in transferring 
grain from one bin to another, a transaction known as “running,” they have 
observed hot spots in the grain at which there would be a “ball of insects.” 
Because of the value of the grain, the necessity for prompt action on the part of 
the owner if heating grain is to.be kept from spoiling, and the reticence of most 
owners to confide specific instances of difficulty to those who may inadvertently 
transmit trade information to competitors, it is extremely difficult to gain a 
first-hand knowledge of this so-called “balling-up” of grain pests at points in 
large elevators. While the writers are not prepared to state that grain pests 
do make a practice of congregating in cold weather to develop a temperature 
making possible their continued activity throughout the cold months, they 
believe that this does happen at times and that this phenomenon offers an inter¬ 
esting field for investigation. The coming together of large numbers of adult 
insects, as in the case of the bran in which Doran recorded finding approximately 
1,500 beetles to the pound, might afford reason for believing that adult insects 
only are capable of starting an increase in the temperature of grain. Without 
denying entirely that adults alone are capable of initiating the heating process 
in grain, the writers are confident that in many instances the developing larvae 
are quite as important, if not more so. 
That the immature stages of Bruchus quadrimaculatus must play a large part 
in the heating of chick-peas would appear from the data of Tables III and IV, 
in which is recorded the infestation of six samples of 50 seeds each, taken from 
sack No. 25 of figure 2, which at the time the samples were taken had in the 
center at 1 foot from the end a temperature of 102° F. These 300 seeds bore 
2,174 unhatched eggs, 527 larvae less than half grown, 453 larvae one-half to full 
grown, 98 pupae, 193 adults about to emerge, and showed indications of 98 adults 
already emerged (though not necessarily living) at the time of examination. 
Assuming that each sample of 50 seeds weighed 1 ounce (as one average sample 
actually did), sack No. 25 contained an infestation of 3,550,960 bruchids in various 
stages of development. Likewise, sack No. 7 (figure 2) with a temperature 
of 89° F., if it had an infestation indicated by the data in Table III, might have 
an estimated infestation of 1,286,640 Bruchus quadrimaculatus in all stages. 
A study of the more detailed data on the infestation of Sack No. 25, as set 
forth in Table IV, will give the reader a very concise idea of the degree of infesta¬ 
tion by Bruchus quadrimaculatus. No such complete data on infestation in 
relationship to heating of wheat as those here given covering the infestation of 
chick-peas had ever been presented. The writers present in Tables V and VI, 
as a report of progress, the rather meager data which they have. 
