INDUSTRIAL FUMIGATION AGAINST INSECTS 



55 



gas through the outlet hose into the elevator legs, spouts, conveyors, 

 rolls, reels, purifiers, and other milling equipment. The dust is 

 retained inside the machine. A dosage of 2 pounds of calcium cy- 

 anide is sufficient for 

 treating four elevator legs 

 and connected spouts and 

 grinders, or for six ordi- 

 nary milling machines. 



One outlet hose from 

 the machine is inserted 

 in each of two elevator 

 legs, and the blower is 

 operated for about 10 

 minutes. The hose is 

 then moved to two other 

 elevator legs and the 

 blower operated for 15 

 minutes. 



Windows in the mill 

 should be kept open dur- 

 ing the fumigation and 

 for 3 hours there after to 

 allow the fumes to escape. 



FUMIGATION OF FLOUR 

 WAREHOUSES 



Warehouses containing 

 flour, feed, or other ce- 

 real products often be- 

 come infested. In the 

 average well-filled ware- 

 house it is impossible, 

 on account of the absorb- 

 ent nature of these com- 

 modities, to obtain a 

 complete kill with the 

 dosages generally used. The killing of insects in the open warehouse 

 and in the outer portions of the bagged material is all that can be 

 expected. For this purpose a dosage of 1 pound of liquid hydro- 

 cyanic acid or its equivalent per 1,000 cubic feet of space with an 

 exposure of 24 hours will suffice. 



Figure 41. — Apparatus for passing air through cal- 

 cium cyanide dust in such a way that the hydro- 

 cyanic acid gas evolved will be free from the dust. 



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 f umigants 

 recommended for vault fumigation, and at the same dosages. 



Bagged flour is fumigated with difficulty, owing to the excessive 

 absorption of the gas by the outer layers of flour. In vault fumi- 



