42 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 6 



completely rid the mill of insect pests and no preliminary cleaning is 

 necessary. 



"It is not dangerous to human life as are all of the other fumigants 

 which are even fairly effective. 



"There is no possibility of injuring floors, belts, or machines, and 

 practicallj^ no danger from fire. 



"The cost of a treatment, after the heating system is installed, is 

 less than one fiftieth of that of hydrocyanic acid gas fumigation. 



"No time is lost in getting ready to use heat. The mill does not 

 need to be shut down several days beforehand, and as most of the 

 Ohio flour mills use steam power, the cost of a heating system would 

 not be prohibitive. High temperature, as compared with other meth- 

 ods of treatment, by saving time and extra expense, will pay for the 

 average heating system required in a flour mill in less than five years." 



Government Recommends the Heat Method.^ During the 

 summer of 1911, the United States Department of Agriculture had 

 one of the experts of the Bureau of Entomology stationed in the 

 southeastern part of the United States to carry on experiments for the 

 control of mill insects in rice and peahut mills. In a recent publication 

 of the results of these experiments, the Government has approved of 

 the heat method and recommends it as a most efficient method in the 

 control of insects in this class of mills. 



The Amount of Radiation Required 



The number of square feet of radiation surface required to heat a 

 given number of cubic feet depends upon the condition and the con- 

 struction of the building, the number of windows and doors on each 

 floor, the character of the machinery, and the location of the steam 

 pipes. Usually one square foot of radiation is sufficient to heat from 

 50-100 cubic feet of space. A mill that has sufficient radiation to 

 heat it in winter to a temperature of 70° without the heat of the run- 

 ning machinery, can readily be heated in summer to a temperature 

 of from 120-125°. 



If the mill is a five-story building, the writer would suggest for the 

 first floor one square foot of radiation to 50 cubic feet of space; for 

 the second floor one square foot to 60 cubic feet; for the third floor one 

 square foot to 75 cubic feet; for the fourth floor one square foot to 90 

 cubic feet; and for the fifth floor one square foot to 110 cubic feet. 

 If the building is four story, one square foot of radiation to 50, 60, 75, 

 and 100 cubic feet of space for the first, second, third, and fourth 

 floors respectively is recommended. 



>Cir. No. 142, Bureau of Entomology, U. S. Dept. of Agr. 



