g CIRCULAR 462, U. S. DEPARTMENT OP AGRICULTURE 



access to the interior of the tubing. A hundred insects were placed 

 in the end of each spike, and the spikes were thrust into the centers 

 of bales of Puerto Rican filler. A thermocouple was also placed in 

 the center of each bale and the lot placed in a refrigerated room held 

 at approximately 13° F. The wooden handle prevented undue con- 

 duction of heat from the bales. Although conditions were somewhat 

 artificial, the results obtained checked very closely with the calcula- 

 tions. The temperature at the center of the bales was 78° at the! 

 start of the experiment and dropped to 18° in 6 days, in which time 

 all eggs and pupae of the cigarette beetle were killed. In Q 1 /^ days 

 the temperature had dropped to 17.5°, by which time all adults were 

 dead. Larvae were killed in about 8y 2 days with the temperature 

 meanwhile falling to 14°. 



SUMMARY 



The cigarette beetle can be controlled by relatively short exposures 

 to low temperature. At 36° F. a 16-day exposure killed all stages 

 and at 25° a 7-day exposure produced complete mortality. 



The larval stage was in general the most resistant at low tempera- 

 tures, but the adult and pupal stages were by far the most resistant 

 at 40° F. 



In the case of eggs, larvae, and pupae the time required to effect 

 complete mortality was the same at 30° and 32° F., and only 1 day 

 longer was required at 36° in the case of the eggs. 



Bales of cigar tobacco when placed in a cold-storage room at 

 approximately 10° cooled down from 64° to 15° F. in from 2% to 5y 2 

 days, depending on the size, shape, and covering of the bale. A 15- 

 day exposure was required for the center of a hogshead of tobacco 

 to drop to 15° in the same chamber. 



Eggs and pupae in the center of bales of Puerto Rican filler, the 

 initial temperature of which was 78° F., were all killed in 6 days 

 after the bales were placed in a cold-storage room held at approxi- 

 mately 13°. Adults in the center of the same bales were killed in 

 6% days, while larvae were all killed in Sy 2 days. 



U. S. GOVERNMENT PBINT1NG OFFICE: 1938 



For sale by the Superintendent of Documents, Washington, D. C. - - - Price 5 cents 



