42 



BULLETIN 1453, U. S. DEPARTMENT OF AGRICULTURE 



ceiling plastered. Since the meat was suspended at all levels in 

 the room, it would appear necessary to use a fan to obtain a more 

 even distribution of heat. 



The rapidity with which heat from heated air penetrates cured 

 meat was the subject of a test in an electric oven. An 8-pound 

 shoulder, old and rather dry, was placed in the oven at 8.35 a. m. 

 Table 18 shows the temperatures during the test. The temperature 

 of the room from which the shoulder was taken was 72° F. 



Table 18. 



-Data showing details of results of heating an 8-pound shoulder in an 

 oven 



Time 



Temper- 

 ature of 

 oven 



Temper- 

 ature of 

 surface 

 of meat 



Temper- 

 ature of 

 center 

 of meat 



Remarks 



8.35 a. m.. .. 



o F 

 124 

 128 

 130 

 128 

 130 

 128 

 132 

 130 

 132 

 130 

 130 

 130 

 136 



F. 



o F 





9 a. m_. 









9.45 a. m.- .. 









10.23 a. m 









11 a. m . 







4 adults of Necrobia rufipes and 2 larvae active on meat. 



12 noon . 





107.6 

 110.3 

 113.0 

 116.6 

 120.2 

 121.1 

 123.8 

 128.3 



2 adults of Necrobia rufipes active on meat. 



12.40 p. m 



1.05 p. m 



2 p. m 



2.40 p. m 



3.15 p. m 



3.45 p. m 



7 p. m 



122 



122.9 

 125.6 

 125.6 

 126.5 

 126.5 

 131 



Several dead larvae of N. rufipes on meat. 



High temperature in an incubator. — Experiments with the expo- 

 sure of adults and larva? to high temperatures in a water- jacketed 

 electric incubator were not satisfactory. When Petri dishes and 

 cotton-plugged vials were used, the exact temperatures to which the 

 larva? and adults were subjected were not known, especially in the 

 case of short exposures. The time required for the air in a stoppered 

 20 by 100 millimeter vial to reach oven temperature was found to be 

 considerable. A vial removed from a room temperature of 78° F. 

 was fitted with a thermometer passing through the tight cotton plug, 

 the bulb being suspended in the center of the vial. This was put in 

 the incubator where the air was 120° and a period of 30 minutes was 

 required for the air in the vial to become heated to 118°. 



In general, it is apparent that adults are killed or seriously 

 paralyzed when confined at 120° F. for half an hour. Migrant larva? 

 were still active after 22 hours' exposure to 110 to 112° ; they were 

 able to skip following 69 minutes in a temperature of 120° ; others 

 formed puparia after being heated for three hours at 118 to 122° ; 

 some recovered after four hours at 122 to 124° ; and larva? became 

 active after 40 minutes at 126 to 128° F. After allowing a liberal 

 margin for slow heat transference, it is evident that migrant larva? 

 of the cheese skipper are resistant to dry air temperatures up to 124° 

 for exposures of several hours. 



Since so little is known as to the shrinkage or possible injury to 

 infested smoked meats heated to temperatures and for lengths of 

 time which would be larvicidal and at the same time practical to use, 

 the writer does not recommend the use of dry heat to kill skippers in 

 smoked meats. 



