26o Journal of Agricultural Research voi. vi, No. 7 



CONCLUSION 



From the data secured during experimental work reported on the fore- 

 going pages, including observations on 173,318 pupae of the Mediterra- 

 nean fruit fly (Ceratitis capitata Wied.), it appears that no pupae survive 

 refrigeration for longer periods than is necessary to cause the death of 

 eggs and larvae in host fruits held at corresponding temperatures. 



About 50° F. is the critical point below which development can not 

 take place and below which death will follow if refrigeration is continued 

 sufiEiciently long. At 49° to 51° only 9 out of 39,500 pupae yielded 

 adults in refrigeration 20 to 47 days after the inward date, while 3 out 

 of 6 held at 52° to 56° yielded adults in refrigeration 38 to 52 days after 

 the inward date. Many pupae can complete their entire development in 

 refrigeration at 54° to 57°, while higher temperatures, not considered 

 here, merely retard development without causing noticeable mortality. 



Pupae can not withstand temperatures below 50° F. for prolonged 

 periods of time. Only 3 and i pupa survived refrigeration for 8 and 9 

 days, respectively, at 32°, while none of 4,500 pupae survived 10 days at 

 this temperature. Refrigeration at a temperature averaging 34°, but 

 ranging between 33° and 36°, proved fatal after the seventeenth day; 

 6,017 pupae refrigerated at this temperature for 18 and 25 days yielded 

 no adults, while the number to yield adults after refrigeration for 14 and 

 17 days was very small. No pupae survived refrigeration at 28° to 40° 

 but averaging 36°, for more than 10 days. A temperature of 38° to 40° 

 proved fatal after the nineteenth day; 30,731 pupae refrigerated for from 

 21 to 35 days failed to yield adults on removal to normal temperatures. 

 After refrigeration at 40° to 45° pupae from each of two lots removed 

 after refrigeration for 24 and 27 days, respectively, yielded adults; 500 

 pupae removed after refrigeration for from 31 to 34 days proved to be 

 dead. 



It does not seem safe to conclude that the age of the pupa has a direct 

 bearing upon its ability to withstand the more ordinary ranges of cold- 

 storage temperatures. 



