64 BULLETIN 536, U. S. DEPARTMENT OF AGRICULTURE. 



DURATION OF ADULT LIFE. 



WITHOUT FOOD. 



If adults have no opportunity to feed after emergence they die 

 within 4 days. Ninety adults issuing on March 15 and kept under 

 starvation conditions were all dead by the end of the third day. On 

 the second and third days, 68 and 22 adults, respectively, died, and 

 at 9 a. m. on the third day only 4 were barely alive, and these were 

 dead by 5 p. m. Of 50 adults emerging on March 14, 1, 48, and 1 died 

 on 1, 3, and 4 days later. French states that he found that adults 

 died in Australia within 4 days if kept without food. The writers 

 have handled many thousands of adults during the past S years and 

 have never had flies live longer. 



If given only water, life is slightly prolonged. Of 300 adults emerg- 

 ing on October 17, 250 had died by the end of the second day, while 

 the remaining 50 were dead by the end of the third day. Of 42 adults 

 emerging May 20, 12, 25, 4, and 1 died after 2, 3, 4, and 5 days. 



WITH FOOD. 



In 1899, Lounsbury in South -Africa confined adult flies in a wire 

 cage out of doors to determine the length of adult life. By the use of 

 apples as food, 1 female out of an original number of 60 was kept 

 alive from March 30 to July 19, or about 16 weeks. French states 

 that adults live to be 25 days old during March in Victoria, Australia. 

 Gurney found that in confinement adults five from a few days to 

 three weeks. Newman states that he has found that flies live usually 

 6 weeks, but when no suitable food is available for oviposition, they 

 may five from 8 to 10 weeks. Later the same writer gives the length 

 of adult life in western Australia as ranging from 28 to 40 days in 

 summer and from 28 to 65 days in winter. 



The writers have found that even when given the best of care many 

 adults die very young. In every lot confined in jars about 50 per 

 cent may be expected to die during the first 2 months. The early 

 death of many flies does not seem to be caused always by overcrowd- 

 ing, for frequently single adults given the best of care in separate jars 

 die at all ages from 1 to 2 days on. The greatest interest in connec- 

 tion with the longevity of adults must center in the minority that live 

 for long periods. 



In a preliminary paper the writers record 1 adult that lived from 

 December 31, 1913, to May 11, 1914, or 131 days, and others emerg- 

 ing on February 28, 1914, that were still alive on August 1, or 5 months 

 after emergence. Additional data have since been secured. One 

 female emerging on the same date died on September 4, or at the 

 age of 5 months ; another female emerging on the same date died on 

 September 30. About 500 adults emerging on June 28 were placed 

 in large glass jars; on August 14 only 40 were still living. The last 

 two of these 40 adults died on October 2, at the ago of 97 days. The 



