INJURIOUS INSECTS OF 1904. 27 



Co-operation: 



Co-operation on the part of all millers, particularly where mills 

 are in the same district, seems absolutely necessary. If one fumi- 

 gates returned sacks, and goes to the expense of freeing his mill 

 of this pest, all should. Otherwise, moths from the untreated 

 mills are almost sure to enter a cleaned mill, rendering the work 

 of the more careful miller, in this connection, of little value. 

 Screening windows and doors might be resorted to, and form at 

 least a partial protection, though occasioning additional expense. 

 Observations at the Experiment Station indicate that the moth 

 cannot pass through the mesh of ordinary wire mosquito netting 

 (144 meshes to the square inch). 



Freesing: 



This most excellent and inexpensive method is available for 

 Minnesota millers during almost any winter. The spouts, elevator 

 legs, purifiers and all machinery should be first freed from masses 

 of webbed flour, etc., left open (this does not mean the unscrewing 

 of the sides of the elevator legs or spouts), and then all windows 

 thrown open for a period of four or five days, after which win- 

 dows should be closed and heat turned on. The importance of 

 exposure to heat after the freezing must not be underestimated. 

 The owners of one infested mill stopped their machinery this win- 

 ter, opened all machines, spouts and elevators to allow access of 

 cold air, and then kept their windows open for a period of four 

 days. This was done in a time of extremely severe weather, the 

 thermometer ranging at the time from ten degrees below zero 

 to thirty-two degrees below, the average temperature of the mill 

 during that period being five degrees below zero. At the expira- 

 tion of this period windows were closed and heat turned on. Some 

 larvae ("worms") and moths collected, and, subjected to examina- 

 tion for several days, did not revive, killed by the extreme cold, 

 aided possibly by the sudden change from warm to cold and cold 

 to warm. Eggs subjected to the above freezing, and kept under 

 observation for fifteen days and over, did not hatch ; nor did 

 the weevils, and other pests found with the Flour Moth, survive 

 this treatment. These statements were made to the \yriter; they 

 are not his observations. 



