44 CIRCULAR 3 6 9, U. S. DEPARTMENT OF AGRICULTURE 



satisfactory results. Chloropicrin is often used as a fumigant in 

 special farm storages. 



In packing houses or storage sections where fumigation chambers 

 or fumigable storage bins are not isolated, a fumigant that does not 

 have the fire hazard of carbon disulphide is desirable. In such cir- 

 cumstances ethylene oxide or a mixture of ethylene oxide and carbon 

 dioxide can be used. Ethylene oxide at the rate of 2 pounds, or the 

 ethylene oxide-carbon dioxide mixture at the rate of 20 pounds, per 

 1,000 cubic feet of space should be for a period of 24 hours. 



Hydrocyanic acid can also be used in airtight vaults at the rate of 

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

 feet. Hydrocyanic acid gas is absorbed in considerable quantities 

 by dried fruit, but is quickly given off after the fruit is aerated. 



Figure 38. — Rug-storage vault in which rugs are protected against fabric pests by 

 vapors of paradichlorobeuzene or flake naphthalene. 



TREATING THE FINISHED PRODUCT 



It is sometimes desirable to fumigate the finished package prior 

 to shipping it from the packing plant. For this purpose a fumiga- 

 tion room or a vacuum tank is necessary. If a fumigation chamber 

 is used, the fumigants and dosages recommended for the raw prod- 

 ucts can be used. If vacuum fumigation is resorted to, excellent 

 results can be obtained with a dosage of 30 pounds of the ethylene 

 oxide-carbon dioxide mixture per 1,000 cubic feet for a period of 

 from 1 to 2 hours. 



INFESTATIONS IN WAREHOUSES 



Infestations that develop in storage warehouses can be handled by 

 fumigating the infested fruit in a fumigation chamber or vacuum 

 tank or by fumigating the entire storage section with hydrocyanic 

 acid. If the entire storage section is fumigated, a dosage of from 

 8 to 16 ounces of liquid hydrocyanic acid or its equivalent per 1,000 

 cubic feet of space should be used for a period of 24 hours. The 

 dosage will depend on the tightness of the storage section and the 

 quantity of fruit in storage. 



