142 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 4 



appreciation of entomology here, and have a corner on that subject 

 SO far as the university is concerned. This institution opens its arms 

 to you — every door and every place you want to go into is yours. 



President Sanderson: The next paper will be given by Mr. George 

 A. Dean, Manhattan, Kan., on "Fatal High Temperatures for the 

 Control of Mill Insects." 



HEAT AS A MEANS OF CONTROLLING MILL INSECTS^ 



By George A. Dean, Manhattan, Kan. 



In connection with investigations relative to the inspection and 

 fumigation of flour mills, the writer noticed on several occasions that 

 the common mill insects were dead, although they were surrounded 

 with an abundance of food. Upon further investigation it was 

 observed that these insects were most frequently found dead in those 

 parts of the mill where, owing to the surrounding conditions, they 

 could easily have been subjected to a temperature varying from 

 105° to 120° F. for four or five hours per day and for a period of several 

 days. 



On looking over available literature relative to the control of this 

 class of insects, it was found that the French long ago knew the value 

 of heat and devised contrivances, called insect mills, for the heat- 

 ing of infested grain. Experiments made by Prof. F. M. Webster 

 in 1883 to ascertain the amount of heat required to destroy the An- 

 goumois grain moth gave these results, "a temperature of 140° F., 

 continued for nine hours, literally cooks the larvae or pupae. A tem- 

 perature of 130° F., for five hours, is fatal, as is also 120° for four hours, 

 while 110° applied for six hours was only partially effective." It was 

 also found in his experiments that wheat could be subjected to a 

 temperature of 150° for eight hours without impairing its germinat- 



iThis paper embodies the results of some of the investigations undertaken by the 

 writer in the prosecution of project No. 58, " Insects Injurious to Stored Grain and 

 Stored Grain Products," of the Kansas State Agricultural Experiment Station. 



The writer desires to acknowledge the valuable assistance rendered by Mr. R. M. 

 Caldwell in carrying out laboratory experiments, and by Mr. Caldwell and Mr. F. B. 

 Milliken in fumigating various mills with hydrocyanic acid gas, and in making 

 trials of heat as a method of destroying mill insects in the large mill where the prac- 

 tical tests were made. 



