CONTROL OF INSECTS ATTACKING STORED TOBACCO 27 



MOVEMENT OF TOBACCO 



From most large warehouses there is normally a constant movement 

 of aged tobaccos into channels of manufacture or into the export trade 

 and of the new-crop tobaccos into storage from redrying plants. 

 Sometimes lots of partly aged tobacco are transferred from one ware- 

 house to another or from small warehouses into the large storage 

 centers. Records from one large closed warehouse in Richmond show 

 that in 3,318,000 cubic feet of space 3,024 hogsheads of flue-cured 

 tobacco, each weighing about 1,000 pounds, which had been stored for 

 1 year or longer in other localities, were moved in over a period of 6 

 months. These old tobaccos as a rule are not segregated but are 

 stored in the various warehouse sections according to grade. This 

 movement of tobaccos often reinfests the warehouse, and it is an 

 important factor in determining the number of periodic fumigations 

 required during the season for the most satisfactory control. 



SCREENING OF WAREHOUSES 



The installation of an 18-mesh steel or copper screen over all open- 

 ings in the warehouse prevents the dispersal of adults of the cigarette 

 beetle and the tobacco moth during the emergence of broods. This is 

 a most important factor in preventing the reinfestation of closed ware- 

 houses that have been freed from insects. Great variation exists in the 

 insect populations in different sections of the same storage, and unless 

 the warehouses are protected by screens the insects disperse into all 

 sections and the cost of control is increased. The screened warehouses 

 are protected also from migrating insects which originate in foods of 

 these pests other than tobacco. These foods are listed on pages 6, 8, 

 and 11 of this circular. 



Control by Chamber Fumigation 



atmospheric chambers 



Small chambers equipped for the fumigation of tobacco at atmos- 

 pheric pressure are used satisfactorily in many tobacco warehouses 

 and factories. This equipment may be constructed in several sizes 

 and types to fit the individual need and may be built of wood and 

 tar paper, metal, or brick. For the most efficient service the chamber 

 should be made tight by equipping it with refrigerator-type doors 

 and covering it inside with a good grade of cement or two coats of 

 paint. Several fumigants have given satisfactory results in chambers 

 of this type. All fumigants are more or less poisonous. The char- 

 acteristics of the kind to be used should be known and all neces- 

 sary precautions against this fumigant should be taken. See 

 pages 30 and 31. Chambers such as these should be installed in 

 tobacco-storage warehouses for the fumigation of infested tobacco en 

 route to the factory or of incoming lots of infested tobacco for storage. 



HYDROCYANIC ACID GAS 



From Liquid Hydrocyanic Acid 



Liquid hydrocyanic acid can be used satisfactorily in small chambers. 

 If chambers are located inside a warehouse, all workers around the 



