50 



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



fly paper under electric lights in warehouses to serve as indicators of 

 the abundance of the insects. Whenever 50 adult cigarette beetles or 

 30 adult tobacco moths are caught on one indicator in a week, it is well 

 to fumigate. 



Two or more fumigations are usually required in one season. For 

 light to moderate infestations a dosage of 10 ounces of liquid hydro- 

 cyanic acid or its equivalent should be applied, whereas heavy in- 

 festations should receive 16 ounces per 1,000 cubic feet. The exposure 

 should be for 72 hours if this does not interfere with warehouse 

 routine. 



For the fumigation of tobacco factories a dosage of 8 ounces of 



Figuke 37. — Tobacco in bales and stacked as closely as shown here cannot be 

 fumigated satisfactorily by ordinary atmospheric fumigation. The bales should 

 be either more loosely stacked or removed to vacuum chambers for fumigation. 



liquid hydrocyanic acid or its equivalent per 1,000 cubic feet for a 

 period of 24 hours is sufficient. 



To keep down infestation in tobacco factories, many firms fumi- 

 gate all incoming tobacco in atmospheric vaults or vacuum chambers. 



For use in atmospheric vaults hydrocyanic acid at a dosage of 10 

 ounces of liquid hydrocyanic acid or its equivalent, ethylene oxide 

 at the rate of 2 pounds, ethylene oxide-carbon dioxide mixture at 20 

 pounds, or carbon disulfide at 10 pounds per 1,000 cubic feet of space 

 should be used for a period of from 48 to 72 hours. Carbon disulfide 

 should not be used unless the vault is isolated from the rest of the 

 buildings and the fire hazard can be controlled. The fumigation of 

 an entire tobacco warehouse with carbon disulfide is a dangerous pro- 

 cedure and is not recommended. 



