INDUSTRIAL FUMIGATION AGAINST INSECTS 41 



because they are used in large quantities in the manufacture of 

 candy, they constitute an important source of insect infestation in the 

 candy factory. 



Most firms handling nut meats attempt to ship only insect-free 

 nuts. To do this they keep their factories and storage warehouses 

 as free from infestation as possible, in addition to fumigating all 

 outgoing merchandise. A yearly fumigation of the factory with 

 hydrocyanic acid gas, supplemented by constant attention to clean- 

 liness, will reduce insect infestation to a minimum. A dosage of 8 

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

 feet is sufficient for this purpose. An exposure of 24 hours is 

 desirable. 



Where nut meats in the shell are stored without cold storage, it 

 sometimes becomes necessary to fumigate the warehouses also. Hydro- 

 cyanic acid is the best fumigant for this purpose and should be applied 

 at the rate of 16 ounces of liquid hydrocyanic acid or its equivalent 

 per 1,000 cubic feet. Excellent results can be obtained in tightly 

 constructed warehouses, even though the bagged nuts are piled in 

 large stacks. If possible, a 48-hour exposure should be given. 



Nuts absorb considerable hydrocyanic acid gas, and therefore a 

 warehouse that has been fumigated cannot be aired out very quickly. 

 Large stacks of bagged nuts hold the gas and give it off slowly over 

 a period of several days. In one fumigation conducted by the writers 

 in an exceptionally tight warehouse, bagged peanuts retained so much 

 of the gas that it was unsafe for workmen to enter the warehouse 

 until it had been aired for 5 days. When ventilation is ample, how- 

 ever, workmen can usually enter the following morning, after the gas 

 escaping from the sacked nuts during the night while the warehouse 

 is closed has been blown out of the main aisles. 



VAULT FUMIGATION FOR NUTS 



Nuts are usually fumigated in atmospheric vaults or vacuum tanks 

 before they leave the factory or go from the storage warehouse to the 

 factory. A 1,000-cubic-foot atmospheric vault will hold about half 

 a carload of bagged nuts, such as peanuts — about two hundred and 

 fifty 100-pound bags of shelled peanuts or 125 such bags of peanuts 

 in the shell. 



A dosage of 3 pounds of ethylene oxide or 25 pounds of the ethylene 

 oxide-carbon dioxide mixture per 1,000 cubic feet of space, with an 

 exposure of from 20 to 24 hours, will give excellent results at a cost of 

 from 1 to 3 cents per 100-pound bag, including labor charges. 



The mixture of carbon dioxide with methyl formate may be used 

 at a dosage of 30 pounds per 1,000 cubic feet of space. 



Hydrocyanic acid can also be used for fumigating nuts in atmos- 

 pheric vaults, although it is not so popular for this purpose as 

 ethylene oxide. A dosage of one-half pound of liquid hydrocyanic 

 acid or its equivalent is required for each 1,000 cubic feet of space. 



VACUUM FUMIGATION FOR NUT MEATS 



For the vacuum fumigation of nuts the ethylene oxide-carbon dioxide 

 mixture is excellent. A dosage of 30 pounds per 1,000 cubic feet for 

 a period of from 1 to 2 hours gives satisfactory results at a cost of 



