• INDUSTRIAL FUMIGATION AGAINST INSECTS 47 



Vacuum fumigation is sometimes used for the treatment of tightly 

 baled tobacco (figs. 31 and 32). In order to penetrate the bales and 

 to insure a quick kill, large quantities of fumigant are necessary. 

 A dosage of from 3 to 5 pounds of liquid hydrocyanic acid or 45 

 j)ounds of the ethylene oxide-carbon dioxide mixture per 1,000 

 cubic feet is required for a 2%-hour exposure. 



FLOUR 



For controlling insects in flour mills and reducing insect damage 

 to milled products, some form of fumigation is usually practiced. 

 Many millers are satisfied to fumigate their mills once a year, while 

 others find it profitable to fumigate several times a year. One 

 thorough fumigation a year will usually control the Mediterranean 

 flour moth (Ephestia kuehnieUa Zell.). but the various flour beetles 

 are not so easily controlled. 



PREPARING THE MILL FOR FUMIGATION 



On account of the milling machinery the preparation of a flour 

 mill for fumigation is more of a problem than is the case in the 

 ordinary building. Instead of each floor being treated separately. 

 the whole building is considered as a unit. In addition to the ordi- 

 nary procedure for preparing a building for fumigation, the direc- 

 tions suggested by Dean and Schenk 6 should be followed : 



Before Stopping Mill 



1. Shut off feed (wheat) at mixing bin. 



2. Continue running all machinery until material is emptied from spouts, 

 elevators, conveyors, rolls, sifters, reels, purifiers, feed duster, suction trunk- 

 ing, and dust collectors. 



3. Meanwhile, hammer elevator legs, machinery, frames, tubular dust collec- 

 tors, and spouts with a rubber mallet or other device which will not bruise 

 or injure the equipment. 



After Stopping Mill 



1. Open all machines, elevator boots, conveyor boxes, and flour bins. 



2. Remove covers of all conveyors, making certain that all dead-end spaces 

 are readily accessible. 



3. Thoroughly clean all conveyors, including dead-end spaces. 



4. Clean out accumulations from bottom section of the bran duster. 



5. Clean all elevator belting that may be webbed ; drag spouts of same. 



6. Remove the adjustable feed gage above grinding rolls and clean out 

 accumulations above rolls and feeders. 



7. Examine tubular dust collectors and clean out all accumulations. 



8. Clean out suction trunks, conveyors, and dust-collector systems. 



9. Open dust-collector trap boxes, main trunks, and hand openings. 



10. Loosen all sifter doors to permit entrance of gas during fumigation. 



11. Leave every machine open; also all hand openings to spouts, elevator 

 legs, etc. 



12. Remove and burn all infested materials accumulated in cleaning the mill. 



13. All infested lots of flour and other milled products should be removed 

 (or reconditioned) before cleaning the mill. These products should not be 

 returned. 



14. If the above procedure is followed, no accumulation of more than 1 inch 

 in depth will be present in the mill. 



15. Special attention should be given to the cleaning of the "dead" spouts 

 and " dead " spaces in corners of spouts and machines. 



16. Remove all bags and other materials used to plug spouts. 



6 Dean, G. A., and Schenk, G. the control of stored grain and flour mill 

 insects. Fourth Internatl. Cong. Ent. Trans. (1928) 2:217-218, illus. 1929. 



