INSECTS INJURIOUS TO STORED GRAINS 199 



ments with sulfur dioxid, produced by burning sulfur slightly wet 

 with alcohol, and finds that it will effectively kill grain insects 

 but injures the germinating power of the grain. " It was found that 

 the fumes produced by burning 2 pounds of sulfur either in a 

 moist or dry atmosphere of 1000 cubic feet space, for twenty 

 hours, would kill all exposed adult insects and practically all the 

 young stages in the grain, but that this also destroyed its germinat- 

 ing power. . . While this treatment cannot be recommended 

 for general fumigation, there is no doubt of its being the easiest 

 and cheapest method of fumigating corn cribs, granaries and 

 similar places whenever they are being cleaned out and freed 

 of insects in preparation for the reception of more grain." 



Heat. The heating of grain was one of the earliest means 

 known of combating grain insects, but has been little used in this 

 country. Recently, however, Mr. Geo. A. Dean of the Kansas 

 Agricultural Experiment Station,* has shown that by super- 

 heating mills they may be rid of insect pests much more quickly 

 and cheaply than by fumigation, and with no risk from fire, or 

 from cyanide poisoning. His experiments show that if the 

 temperature surrounding an insect be maintained above 120 F., 

 with a normal amount of moisture, that in a very few minutes it 

 will be killed. This promises to become one of the most prac- 

 ticable methods of cleaning mills and may be used for small 

 quantities of grain, where there are facilities for heating it or 

 placing it in a superheated room, but probably carbon bisulfide 

 fumigation will be found more practicable for small amounts. 

 * Geo. A. Dean, Journal of Economic Entomology, Vol. IV, p. 142. 



