INDUSTRIAL FUMIGATION AGAINST INSECTS 49 



As indicated on page 48, there are several ways of applying the 

 gas, but the most effective method is to introduce the entire dosage 

 for the building into the machinery itself. If the machinery is run 

 for a short time while the gay is being applied, the vapor will be 

 distributed to all parts of the mill. 



The vapors of chloropicrin have a deleterious effect on the baking 

 qualities of flour, but flours fumigated with chloropicrin show com- 

 plete recovery after being properly aerated. After a fumigation 

 with chloropicrin, it is advisable to lay aside the first few bags of 

 flour that come through the mill and feed them back slowly into 

 the mill. In this way the chloropicrin is soon dissipated. 



LOCAL FUMIGATION 



Since insect infestation in a flour mill is confined largely to the 

 machinery, many millers prefer to fumigate the machinery alone 

 instead of the entire mill. The cubic content of the machinery being 

 only a fraction of that of the mill, the miller can afford to fumigate 

 more often. With a little sealing and plugging, each machine can be 

 separated from the others and fumigated when necessary. Instead of 

 only on week-ends, this type of fumigation can be utilized any night 

 after the mill is shut down. Hydrocyanic acid, chloropicrin, ethylene 

 dichloride-carbon tetrachloride mixture, or the ethylene oxide-carbon 

 dioxide mixture can be used. The machinery can be specially piped 

 and the fumigants sprayed in through nozzles, or the liquids can be 

 applied by hand. Two or three times the ordinary dosage for general 

 mill fumigation can be used in the machinery without great expense. 



As in regular mill fumigations, the operator should wear a gas mask 

 when applying the fumigant and also when airing out the machinery 

 the following morning. 



FUMIGATION OF FLOUR WAREHOUSES 



It is often desirable to fumigate warehouses containing flour, feed, 

 or other cereal products. A complete kill cannot always be obtained, 

 however, since fumigants will not penetrate more than 1 or 2 inches 

 into bagged flour. Fortunately, insect infestation of bagged flours is 

 usually near the surface, and under favorable conditions the kill is 

 good enough to make fumigation well worth while. A dosage of 8 

 ounces of liquid hydrocyanic acid or its equivalent per 1,000 cubic 

 feet of space for from 17 to 24 hours should be used. 



VAULT FUMIGATION FOR FLOUR OR CEREAL MILL 



For the treatment of used bags, returned goods, or small lots of 

 infested flour or cereals, a fumigation vault is almost essential. The 

 vault can be of any of the types discussed on page 28. If possible, it 

 should be located in a building separate from the main mill, so that 

 used bags or returned goods can be fumigated before being taken into 

 the main building. 



Used bags can be fumigated successfully with any of the fumigants 

 recommended for vault fumigation, and at the same dosages. 



