May 1 5. 1916 Cold Storage and Pupcs of Mediterranean Fruit Fly 257 



It will be noted that only 9 out of 300 pupae survived refrigeration for 

 16 days, while only 4 out of 500 and i out of 500 refrigerated for 18 and 

 24 days, respectively, survived. Three hundred pupae refrigerated for 

 31 days and 200 refrigerated for 34 days were found dead on removal. 



Temperatures of from 49° to 5 1 ° F. — Temperatures ranging between 

 49° and 5 1 ° F. and averaging about 50° have proved most interesting of 

 all, as these appear to be very close to the point below which the insect's 

 activities cease. This temperature was secured by use of an ordinary 

 refrigerator 42 by 34 by 18 inches. During the period from May to July, 

 1 914, 31,700 pupae were used in an experiment to determine the efifect 

 of this temperature upon pupal development. Pupae in 15 lots, of ages 

 ranging from i to 8 days, and averaging 3,523 pupae for each of the 8 days 

 represented, were held in storage for two months before removal. Fre- 

 quent observations were made but no pupae completed their development 

 and yielded adults in storage. On removal to normal temperature all of 

 the 31,700 pupae were found dead. 



The second lot of 7,800 pupae placed in storage when 5 days old yielded 

 a few adults. Thus, 9 out of 7,800 yielded i, 2, 2, 3, and i adult in 

 storage after refrigeration for 20, 23, 44, 46, and 47 days. In other 

 words, it took these 9 pupae from 20 to 47 days to accompHsh the develop- 

 ment in refrigeration which at an outdoor temperature at that season, 

 July, 1 91 4, would have taken only from 4 to 5 days. 



Temperatures of from 52° to 56° F. — Ten larvae pupating in a 

 refrigerator held at 52° to 56° F. yielded 2 and i adult in storage after 

 refrigeration for 38 and 52 days, respectively. The remaining 7 pupae 

 died. 



Temperatures of from 54° to 57° F. — Temperatures of from 54° to 

 57° F. were obtained by using an ordinary refrigerator 46 by 27 by 18 

 inches. A total of 22,700 pupae were used varying in age from ^ to 9 

 days. Not less than 1,400 pupae, or more than 3,500 pupae of any age, 

 were used. In Table VI are recorded the reactions of 3,100 one-day-old 

 pupae to these temperatures. 



From the data in Table VI it will be noted that 54° to 57° F. is not 

 in all cases fatal to pupal development, although a high mortality occurs. 

 Each outward date represents 100 pupae. As the heavy line extending 

 diagonally across the table indicates the dates on which pupae were 

 removed from refrigeration, and as the normal pupal development is 

 completed at this season of the year at Honolulu in from 9 to 1 2 days, the 

 data prove that development continues at this temperature as evidenced, 

 first, by the rate of emergence of adults after the pupae are removed from 

 refrigeration up to the thirtieth day of refrigeration, and, secondly, by 

 the emergence actually occurring within storage on the thirty-first day 

 and up to the thirty-seventh day of refrigeration. Thus development 

 was wholly completed and emergence had taken place at this temper- 

 ature among pupae removed from refrigeration after 37, 38, and 39 days. 



