This laboratory-based study provides baseline life cycle data for the obligatory parthenogenetic earthworm Octolasion cyaneum. Singleton and twin hatchlings were cultured individually with biomass, survival and reproductive condition recorded at 4-weekly intervals during a complete year. After maturation, cocoon production, masses and incubation time were also recorded along with viability and number of hatchlings per cocoon. Individual mean mass of singletons was significantly (P<0.05) greater than twins at the outset (0.042 and 0.025g respectively) and remained so until week 52 (2.22 and 1.96g respectively). Singletons matured more rapidly than twins (24 vs. 32weeks respectively) and produced more cocoons than twins (3.2 and 2.2cocworm −1 (4weeks) −1 respectively). Approximately 20% of all viable cocoons produced twins. Singleton hatchlings weighed significantly (P<0.05) more than twin hatchlings (0.032 and 0.018g respectively) but there was no significant difference (P>0.05) between mean masses of singleton (mean masses 0.033 and 0.032g) or twin (0.017 and 0.018g) hatchlings produced by singleton and twin parents. The likelihood that a cocoon contained twins or a singleton was not influenced by the singleton/twin status of the parent. There was no significant difference (P>0.05) in the incubation times of cocoons produced by singletons and twins (129 and 128days respectively).