THE TOBACCO BEETLE. ' 45 



Two tests were made, one in which the room was heated by turning 

 the steam into radiators, and one in which the entire basement of the 

 building was heated by admitting the live steam direct from the 

 boiler. Evaporation during the experiment was about 75 gallons per 

 hour. 



The experiment in the room fitted with radiators was commenced 

 on July 7, the temperature of the room being 85° F. Steam was 

 turned on at 2 p. m. 1 All stages of the tobacco beetle were used in 

 the experiment and were placed in cans of smoking and chewing 

 tobacco in the middle of the room. Controls were kept for each lot. 

 At 3.30 p. m. the temperature reached 100° F., and at 4.30 p. m. 

 117° F. This temperature was held until 6 p. m. and then gradually 

 lessened until 7 a. m., July 8, when it registered 89° F. The steam 

 was again turned on and the temperature gradually increased until, 

 at 10 a. m., it registered 138° F. This temperature was held until 

 noon, when the experiment was ended. At different times some of 

 the material was taken out and the boxes labeled and kept for later 

 examination. Tobacco exposed for 2| hours at temperatures between 

 100° and 117° F. when examined on July 8 was found to contain 

 live adults, pupse, and larvae. In all material kept in the room 

 during the entire time, and which had been subjected to a tem- 

 perature of 138° F. for 2 hours, all stages of the beetle were killed. 

 In this experiment the air was dry. A hygrometer at 6 p. m. 

 registered about 35° F. 



In the second experiment the entire basement of the building was 

 heated by live steam which was admitted directly through four 

 half -inch nozzles. Three nozzles were fitted to the main steam pipe 

 extending through the basement from end to end, and one nozzle 

 fitted to the return pipe. Records of temperature were secured 

 by means of self-recording thermometers placed in or near the 

 packages of infested tobacco, which were divided into several lots 

 and placed in different parts of the basement. The tobacco used 

 in the experiment was badly infested with all stages of the beetle. 

 The experiment was commenced at noon. The outside temperature 

 in the shade was 92° F. A boiler pressure of 40 pounds was kept 

 until noon of the following day, July 9, when the fire under the 

 boiler was allowed to die out gradually to avoid too sudden cooling 

 of the walls of the building. The tobacco used in the experiment 

 was taken to Tampa, Fla., and kept under observation until July 

 15. The results were as follows: At temperatures under 114° F., with 

 exposures of 6, 12, and 18 hours, results were practically negative. Ex- 

 posure at temperatures between 118° and 130° F. for 24 hours killed 

 part of the different stages, but was not entirely effective. Mate- 



1 All references to clock time refer to standard time. 



