February, '10] HINDS AND TURNER : CARBON DI-SULFID 55 



cracks were battened with, lathing nailed as tightly as possibly along 

 them and partitions of matched boarding constructed so as to form 

 three adjacent sections, each containing approximately 100 cubic feet. 

 This corn had but recently been husked and placed in storage, and 

 practically all weevil stages present were alive. Temperature and 

 humidity records were kept here also. To add if possible to the tight- 

 ness of the room, gas-tight tarpaulins were hung outside the walls, 

 reaching from a height above the level of the corn to the ground. The 

 corn was also covered with a similar tarpaulin. In this case Fuma 

 di-sulfid was applied at the rates of 10, 15 and 20 pounds per 1,000 

 cubic feet. The temperature at the beginning of the treatment stood 

 at 47 degrees F., but fell during the next two hours to 35 degrees. 



During the succeeding thirty-six hours after this minimum was 

 reached, it rose gradually and steadily to a maximum of 55 degrees, 

 from which point it again fell to 35 degrees and subsequently two 

 minimums of 32 degrees were reached with the maximum never ex- 

 ceeding 53 degrees. The unusually low temperature prevailing is- 

 doubtless sufficient explanation for the fact that in none of these sec- 

 tions was there more than 15 or 20 per cent mortality among the 

 adult weevils, even where the largest dosage was applied. In con- 

 clusion, it would appear that the important results obtained from these 

 experiments are as follows : 



Grain infesting insects may be destroyed with carbon di-sulfid, 

 cheaply and effectively, by even an application of 5 pounds per 1,000 

 cubic feet in exceptionally tight compartments, while the temperature 

 is above 70 degrees F. It requires but a few hours to kill the weevils 

 if a strength of gas equal to one quarter of a saturated atmosphere 

 can be maintained, and provided the temperature is high enough to 

 insure a considerable degree of vital activity on the part of the insects. 

 Fumigation work with temperatures ranging below 60 degrees F. ap- 

 pears to be largely ineffective and inadvisable. Particularly in the 

 Southern States, it would be possible to make the applications so that 

 the temperature during the next few hours will average above 60-65 

 degrees. While the results obtained have been in some degree disap- 

 pointing, we believe that they indicate a possible basis of explanation 

 for variation in the effectiveness of treatments that have been reported 

 in the past. They also show that the conditions under which each 

 application is made constitute a problem by itself, and there is reason 

 to feel that we may ultimately understand the influence of the many 

 factors involved sufficiently well to enable us to adjust our methods 

 of treatment so that they may produce more uniform and more satis- 

 factory results. In spite of the many drawbacks to the common use of 



