The Biology of Ageing in Insects 



257 



from the earlier study on diet (Rockstein, 1957), and the more 

 recent total of over 4,000 flies per sex, fifty per cent mortality 

 occurred at 16 days for the males and at 30 days for the 

 females, respectively. The mean longevity values for males of 

 about 17 days and for females of about 29 days, for this large 



0.01 I — 



0.05 

 0.1 

 02 



0.5 

 I 



2 



95 



98 

 99 



99.5 



99.8 

 99.9 



• MALES 

 o FEMALES 



/ 



o» 



J I I I I 1 1 II 



J L 



2 3 4 5 6 78910 20 30 40 50 6070 80 



LOG TIME 



Fig. 3. Log-probit plot for male and female housefly 

 survival. 



Reprinted from Rockstein and Lieberman (1959), by courtesy of the Editor, Nature. 



number of flies, also compare favourably with those reported 

 in 1957. The close approximation of mean and medium 

 longevity values is also a strong indication of a good natural 

 distribution in so far as the populations of the two sexes in 

 this strain are concerned. 



A log-probit plot of these data (probability of survival 



AGEING — V — 9 



