38 



CIRCULAR 369. U. S. DEPT. OF AGRICULTURE 



to keep the pump in operation during the unloading process so that 

 a stream of fresh air will be drawn constantly through the tank, 

 thus reducing the concentration to which the workmen are exposed. 

 The temperature of the commodity is an extremely important 

 factor in vacuum fumigation. Cold commodities, particularly highly 

 absorbent materials such as flour products, cannot be treated suc- 

 cessfully unless large dosages are used. A temperature of 70° F. or 

 above is desirable. If possible, commodities taken from cold storage 

 should be allowed to come to room temperature before being treated. 



Figure 



— New type of rectangular fumigation chamber. Note vacuum pump at right, 

 with temperature and vacuum gages and other equipment behind it. 



FUMIGATION OF VARIOUS COMMODITIES 



Since it is impossible to discuss here in detail the fumigation of 

 all the many types of commodities that become infested with in- 

 sects, only those commodities most often fumigated in commercial 

 establishments are included in this circular. The fumigation of dried 

 beans and grain in bulk on the farm and in the terminal elevator is 

 discussed in other publications of the Department. 4 No attempt is 

 made to discuss the fumigation of any commodity from a quarantine 

 standpoint. For more detailed information regarding the treatment 

 of any commodity discussed in the following pages, or regarding 

 commodities not mentioned, the reader should direct inquiries to 

 the Bureau of Entomology and Plant Quarantine, United States 

 Department of Agriculture, Washington, D. C. 



4 Farmers' Bulletin 1260, Stored-Grain Pests ; Farmers' Bulletin 1275, Weevils in Beans 

 and Peas ; and Farmers' Bulletin 1483, Control of Insect Pests in Stored Grain. 



