30 CIRCULAR 8 6 9, U. S. DEPARTMENT OF AGRICULTURE 



ethylene oxide-carbon dioxide fumigant before shipment, particularly 

 in summer. When fumigating cigars it is advantageous to do so 

 before wrapping in cellophane. 



Pipe and chewing tobaccos are rarely fumigated after manufacture. 

 Therefore they must be protected during storage if losses are to be 

 prevented. Adequately sealed packages are valuable in this respect. 

 All returned goods should be fumigated before being received into 

 the factory for cleaning and salvage. 



Heat Treatment and Cold Storage 



As has been stated, the redrying process for leaf tobacco should kill 

 all stages of the tobacco moth and cigarette beetle. This is not neces- 

 sarily true for the redrying of flue-cured strips, the laminae of the 

 leaves after the midribs have been removed. Strips are redried at 

 lower temperatures and for shorter periods than is leaf tobacco ; conse- 

 quently the treatment is not always entirely effective. 



In manufacturing cigarette or pipe tobacco, the shredded, granu- 

 lated, or chopped-up tobacco is heat conditioned. In all such proc- 

 esses observed the temperatures have not been high enough or main- 

 tained long enough to give appreciable insect mortality. 



Cold or cool storage is of great value in preventing or checking an 

 insect infestation. Flue-cured tobacco for export is sometimes held 

 in storage at 50° to 60° F. to prevent loss of color and excessive fer- 

 mentation. As the threshhold of activity for the moth and the beetle 

 is 60° to 65°, a lower temperature will check activity and arrest insect 

 development. 



Cool storage is also widely used in the cigar industry to prevent 

 cigarette beetle infestation. Cigars are often stored in rooms at 45° 

 to 55° F. No insect infestation occurs at this temperature. The 

 cigarette beetle is killed by continuous exposure to 40° for 33 days, to 

 36° for 16 days, to 25° for 7 days, or to 15° for 3 days. 



AN INSECT-CONTROL PROGRAM IN TOBACCO 

 WAREHOUSES 



The question of when and where to fumigate is sometimes difficult 

 to answer. The problem may be complicated by the type or age of 

 the tobacco, the degree of infestation, whether one or both species of 

 insects are involved, and previous treatment. As a rule it is advisable 

 to fumigate a warehouse 1 to 2 weeks after the peak of emergence of an 

 insect brood. However, where the tobacco moth is known to be pres- 

 ent, fumigation as early in the spring as appreciable emergence occurs 

 is desirable. 



Complete kills of insects are rare in the fumigation of tobacco ware- 

 houses. For this reason it is important to keep a constant record of 

 insect populations in Avarehouses by means of suction light traps, and 

 to time fumigation to follow the emergence of beetles and moths. 

 When full grown, tobacco moth larvae move to the surface of the to- 

 bacco or leave it entirely. Large numbers of cigarette beetles also 

 migrate to near the surface of the tobacco. The adult moths and most 

 of the adult beetles stay out of the tobacco to mate and lay eggs. As 

 the eggs of both insects are laid on or near the surface of the tobacco, 



