INSECT CONTROL, IN FLOUR MILLS. 13 



fumigation should advise regarding the need to vacate. Persons 

 should be advised not to remain in rooms closely associated with rooms 

 being fumigated if the odor of the gas can be detected. In numerous 

 fumigations persons have remained at their work even when the odor 

 of the gas was very pronounced, and workmen have been known to 

 carry on trucking operations in warehouses where the odor of the 

 residual gas after fumigation was so strong as to give the writer of 

 this bulletin unpleasant feelings. Rooms adjoining those being fumi- 

 gated should be kept well ventilated, but even then, to remain in them 

 when the odor of the gas can be detected may lead to fatalities directly 

 chargeable to the fumigator. To attempt fumigation without the 

 approval and cooperation of those controlling the occupants of ad- 

 joining buildings may lead to fatalities directly chargeable to criminal 

 neglect on the part of the person conducting the fumigation. 



Guards should be placed at entrances that can not be closed by 

 means of reliable locks to thoughtless intruders. Only trusted men 

 should be employed to assist in any process of fumigation, and this 

 holds particularly true of the person or persons left on guard. One 

 man, at least, is known to have been killed because he was not in- 

 formed of the fumigation, returned for night work, and entered 

 through an unlocked door left temporarily unguarded by a sleeping 

 guard. A genuine responsibility rests upon a person conducting fumiga- 

 tion and he should discharge his duties with all seriousness. He should 

 choose as helpers only the most intelligent and trustworthy employees. 



Preparation of Mill foe Fumigation. 



Preliminary cleaning. — In fumigating a mill the greatest loss of 

 time is caused by the need for preliminary cleaning; the fumiga- 

 tion can be done between Saturday night and early Monday morn- 

 ing or within any period of 24 hours' duration. The reason for 

 thorough cleaning and destruction of flour and accumulations from 

 various parts of the mill is primarily to leave in the mill at the time 

 of fumigation no masses of stocks which the gas must penetrate to 

 reach all the insects. Hydrocyanic-acid gas, deadly as it is, can not 

 be depended upon to reach and kill all moths, pupse, eggs, and larvae 

 if these are buried beneath several inches of well-packed flour, such 

 as often occurs in dead spaces of machines, in floor cracks, basements, 

 etc. The removal and destruction by burning of such accumulations 

 which, as has been stated already, are favored by pests as feeding 

 and breeding places, destroy large numbers of insects, as well as 

 leave the mill in a condition to be fumigated to best advantage. 



Make mill as tight as possible. — The mill should be made as tight 

 as possible, so that the gas generated can not escape before it has 

 had a chance to kill the flour moth. Broken windows, ventilators, 



