Our laboratory work on the life cycle of aquatic Oligochaeta has been extended to the tubificids Potamothrix hammoniensis and P heuscheri, as well as to the lumbriculid Bichaeta sanguinea.Basically we measured the duration of the time required for the embryonic development inside the cocoons, at different temperatures. In addition, cohorts of these species were cultured and the time required to attain the sexual maturation and the cocoon laying stages were estimated.The results concerning these three species are consistent with the field observations, as far as their value as indicator species is concerned, and contribute to a further understanding of the role of biotic factors in determining the distribution and succession of some aquatic Oligochaeta.