May 15. 1916 Cold Storage and PupcE of Mediterranean Fruit Fly 255 



upon to kill all pupae. While an average of about 1,479 pupae were re- 

 moved each day, the number of pupae of each age is not known; hence no 

 conclusion can be drawn regarding the relative effect of this refrigeration 

 upon pupae of different ages. The data given above for 9, 11, 12, 14, 15, 

 and 16 days of refrigeration seem to indicate that the older pupae with- 

 stand the effects of cold for a relatively longer period. 



In a second experiment 50 out of 200 pupae of all ages yielded adults 

 after 4 days' refrigeration, and but 15 out of 207 pupae held at 33° to 

 34° F. for 4 days and then at 43° to 45° F. for 3 additional days. 



Temperatures of from 28° to 40° F., averaging 36°. — A total of 

 8,500 pupae were placed in a cold-storage room the temperature of which 

 was subject to far greater changes than are usual in commercial plants. 

 While the temperature averaged about 36° F. a large portion of the time, 

 for short periods during the night it dropped to freezing or even 28°, and 

 during the heat of the day when supplies were being removed frequently 

 rose to 38° to 40°. As each lot of the various ages from K to 9 days re- 

 moved consisted of 100 pupae, the numbers of pupae yielding adults after 

 the various numbers of days of refrigeration represent the percentages of 

 survival. In Table III are recorded the effects of from i to 24 days of 

 refrigeration on 6,800 pupae. 



Table III. — Effect upon pupce of refrigeration at temperatures varying between 28° and 

 40° F., but averaging about ^6° F. * 



Age of pupae on entering 

 storage. 



Number of pupae yielding adults on removal to normal temperature after 

 refrigeration for— 



I day. 



3 days. 



6 days. 



8 days. 



days. 



days. 



i6 

 days. 



i8 

 days. 



days. 



1 day. 



2 days 



3 days 



4 days 



5 days 



6 days 



7 days 

 9 days 



8i 

 92 

 62 



55 

 70 

 94 

 69 



35 



5 



32 

 21 

 60 



a 27 



14 



51 

 a 27, 



" Of these three lots of 100 pupse each, 25, 17, and 16 pupae, respectively, yielded adults July 8, or just 

 before being placed in cold storage. 



A total of 1 ,700 pupae of various ages removed to normal temperature 

 after refrigeration for 21, 27, 29, and 31 days were found to be dead. 



Temperatures of from 38° to 40° F. — A total of 52,604 pupae were 

 used in experiments to determine the effect upon pupae of refrigeration 

 at 38° to 40° F. An average of i ,860 pupae of all ages were removed after 

 refrigeration for 3, 4, 6, 7, 8, 10, 12, and 14 days. The number of pupae for 

 each age varied from 109 to 414 and averaged 234. The number of 

 pupae surviving refrigeration for from 3 to 14 days is recorded in Table 

 IV. 



