SURVIVORS (l x ) Curves 



for the Black Widow, 



known males and 



Males females only 



SURVIVORSHIP (U) Curves 



Black Widow Males 



Black Widow Females 



DEATH (d x ) Curves 



IO(HO-60-40-?0 +20+40+60+80 +I0O+I2O+WM60H8O 

 Percentage deviation from mean duration of life 



Fig. 34. — Survivorship curves for 82 males and 45 females of the black widow 

 spider Latrodecte smactans (Fabr). Note that the male curve is shown to five 

 times the time scale of the female curve (from Deevey and Deevey, 1 945) . 



Fig. 35. — Survivorship, death and death-rate curves for the black widow. 



Note that the death curves are shown to twice the ordinate scale of the 



others (from Deevey and Deevey, 1945). 



80 160 240 320 400 480 



Fig. 36. — Survivorship curves for male and female Tribolium madens (radix 

 of 1,000 images) (from Park, 1945). 



