INSECT CONTROL IN FLOUR MILLS. 11 



CLEANLINESS IN WAREHOUSE ROOMS. 



Warehouse rooms, as well as the mill proper, should be kept as 

 clean as possible. After each movement of stocks the floor and walls 

 should be cleaned to prevent insects present from holding over to 

 attack a new stock. Xeglect of this simple precautionary measure 

 has resulted in a more rapid infestation of warehouse stocks than is 

 generally appreciated. 



NATURAL CONTROL BY PARASITES. 



In many mills the Mediterranean flour moth is attacked by insect 

 parasites, Hdbrobracon hehetor (Say) and Omorga frumentaria 

 (Rond.), but in no case are these of sufficient importance to warrant 

 a miller depending entirely upon them, although at times they may 

 prove a valuable control factor. They are not a dependable factor in 

 any part of the United States. In a successful fight against the 

 flour moth, control by parasites should not be relied upon. 



ARTIFICIAL CONTROL MEASURES. 



Since the spread of the Mediterranean flour moth from Europe to 

 the milling centers of the United States experimental work has 

 been conducted to determine the most satisfactory methods of con- 

 trol. From the various processes advocated from time to time, such 

 as fumigation with sulphur, carbon disulphid, tobacco fumes, for- 

 maldehyde gas, etc., there have finally emerged two control measures 

 that have now proved their value. These are fumigation with hydro- 

 cyanic-acid gas and control by heat. Where these can be intelli- 

 gently and thoroughly applied results can be guaranteed. Heat is 

 unquestionably the cheapest and simplest agent of control now 

 known. Millers have had varying results in attempts to control the 

 moth with freezing temperatures. 



HYDROCYANIC-ACID GAS TREATMENT. 



Fumigation with hydrocyanic-acid gas, while effective, is a dis- 

 agreeable method of control. The gas generated is deadly to man, as 

 well as to insects, and precautions must be taken to safeguard the lives 

 of laborers and dwellers in closely associated buildings. It is as- 

 sumed for the purposes of this bulletin that no milling concern will 

 attempt fumigation with hydrocyanic-acid gas without calling in the 

 services of an expert familiar with the process. 2 It may be added 

 that where it can be used, hydrocyanic-acid gas fumigation is per- 

 fectly safe when conducted under the immediate supervision of a 



2 For more complete information regarding the use of this gas, write to the U. S. De- 

 partment of Agriculture for publications. 



