Biology of parthenogenetic females of Ceriodaphnia comma Sars was studied under laboratory conditions. The mean length of neonates (first-young instars) of Ceriodaphnia cornuta was found to be 0.27 mm at 25±1℃ and that of the first adult instars 0.50 mm. A maximum length of 0.69 mm was attained at the 8th adult instar.The mean longevity was found to be 19.0 days for 3 preadult and 8 adult instars.Sex maturity was reached in 4.26 days. The mean number of young per brood was 6.21 .The total production for each adult reached 49.7. The maximum reproduction period occurred during the 4th adult instar. At this age, the animals were 10.25 days old, and had a body length of 0.65 mm.The innate capacity for increase (rm) was 0.40 per female per day, the net reproduction rate (R0) was 33.601 per generation , the mean length of a generation (T) was 8.786 days, and the finite rate for increase was 1.492 per female per day.omparisons using the t-test indicated that the number of eggs produced and number of broo t si Biology of parthenogenetic females of Ceriodaphnia comma Sars was studied under laboratory conditions. The mean length of neonates (first-young instars) of Ceriodaphnia cornuta was found to be 0.27 mm at 25 ± 1 ° C and that of the first adult instars 0.50 mm. A maximum length of 0.69 mm was attained at the 8th adult instar. The mean longevity was found to be 19.0 days for 3 preadult and 8 adult instars.Sex maturity was reached in 4.26 days. The mean number of young per brood was 6.21. The total production for each adult reached 49.7. The maximum distribution period occurred during the 4th adult instar. At this age, the animals were 10.25 days old, and had a body length of 0.65 mm. The innate capacity for increase (rm) was 0.40 per female per day, the net reproduction rate (R0) was 33.601 per generation, the mean length of a generation (T) was 8.786 days, and the finite rate for increase was 1.492 per female per day. comparisons using the t-test indicated that the number of eggs produced and number of broo t si