42 BULLETIN 737, U. S. DEPARTMENT OF AGRICULTURE. 



order to avoid sweating which ordinarily would occur upon re- 

 moval from cold storage. When removed from cold storage it 

 was placed in a dry room for several hours, then placed in the 

 humidor or storage room at the cigar store with the control or check 

 packages. At frequent intervals the treated tobacco was compared 

 with check tobacco by Mr. J. M. Holt, a tobacco expert of Richmond, 

 Va., and the writer. The tobacco put in cold storage seemed in per- 

 fect condition in every respect, and could not be distinguished from 

 that which had been kept at the cigar store. 



ALTERNATIONS OF HEAT AND COLD. 



The alternation of a low temperature with a comparatively high 

 temperature is apparently more effective on the tobacco beetle than 

 is a single exposure to cold. During the course of cold-storage in- 

 vestigations at Richmond, Va., in 1914, two lots of badly infested 

 smoking tobacco were put in cold storage for 2 days at temperatures 

 ranging from 14° to 16° F. Lot A was not removed from the stor- 

 age ,room, whereas at the end of 24 hours lot B was removed and 

 kept in a warm room for 24 hours, then put back in cold storage for 

 a further period of 24 hours. On March 22, 2 days after treatment, 

 both lots were examined and no live stages of the beetle were found 

 in lot B. In lot A about 90 per cent of the different stages were 

 dead. The tobacco used in the experiments was kept until August 

 28, 1914, and upon examination lot A was found heavily infested 

 whereas lot B was uninfested. 



HIGH TEMPERATURES. 



EXPERIMENTS WITH DRY HEAT AS A MEANS OF STERILIZING TOBACCO TESTS IN 



TOBACCO FACTORIES. 



Two series of tests were made, one at Richmond, Va., in a factory 

 where smoking tobacco is manufactured, and the other at New 

 Providence, Tenn., in a factory in which special processes are used 

 in the preparation of leaf tobacco for export to Africa. 



Excellent facilities were secured for determining the effect of high 

 temperatures on different stages of the beetle, and for determining 

 to what extent the tobacco is sterilized by the various processes of 

 manufacture. It was found that in these factories the temperatures 

 reached were sufficiently high to kill all stages of the beetle, rein- 

 festation depending on methods of handling, packing, or storing the 

 manufactured product. 



At Richmond, Va. (May, 1915), large numbers of eggs of the 

 tobacco beetle on leaf tobacco and in cells on microscope slides, pupae, 

 adults, and newly hatched and mature larva? were placed in boxes 



