THE TOBACCO BEETLE. 67 



Under laboratory conditions tests made with a Rontgen-ray tube 

 permitting a high-energy input and giving an intense and powerful 

 radiation produced results which promise that the X-ray process may 

 be used successfully in treatment of cigars or tobacco infested with 

 the tobacco or cigarette beetle. 



Heavy dosages must be given, as is indicated by the results of 

 exposures given in several series of experiments. 



In treatment of the egg stage, heavier exposures are required to 

 sterilize eggs which are near the hatching- point than are required to 

 sterilize eggs newly laid. 



In experiments performed by the writer a dosage equivalent to 

 150 milliampere minutes exposure with a spark gap of 5.5 inches 

 gave satisfactory results with eggs in tobacco placed 7.5 inches from 

 the focal spot of the tube. With this exposure the eggs in which 

 embryonic development was well advanced hatched, but in all cases 

 where these larvae were kept under observation they failed to reach 

 the adult stage. 



The minimum lethal dosage at a given distance from the focal spot 

 of the Rontgen tube used was not determined. 



In two separate experiments adults were given an exposure of 

 600 milliampere minutes (amperage X time), with a spark gap of 

 5.5 inches, giving an approximate voltage of 65,000. The distance 

 from the focal spot of the Rontgen tube was 7.5 inches. The results 

 were as follows : 



(1) No effect on length of life was apparent, as the beetles died 

 at about the same rate as the same number of beetles kept as check. 



(2) Large numbers of eggs were deposited after exposure. These 

 eggs were infertile. Eggs laid by the check beetles hatched normally. 



Larvae were given an exposure of 600 milliampere minutes, other 

 conditions of the experiment being the same as in the experiments 

 with adults given above. While no immediate effect was apparent 

 the treatment had the effect of stopping activity and development, 

 the larvae remaining in a dormant condition for a prolonged period. 

 All treated larvae died before reaching the pupa stage. 



Two methods of treating cigars in factories with the X-ray proc- 

 ess are employed at the present time. In one method the finished 

 cigars in closed boxes are conveyed by a belt very slowly through 

 an exposure chamber containing the Rontgen tubes. The walls of the 

 exposure chamber are constructed of thick sheets of lead (lead is not 

 penetrated by the Rontgen rays) in order to protect the operator 

 of the machine from injury. 



In the other method of treatment a large room used as a humidor 

 at the factory was completely lined with sheet lead. In a narrow 

 compartment within the humidor, extending along one side, a 

 series of 16 powerful Rontgen-ray tubes are arranged in two lines 



