In controlled experiments, all ontogenetic instars of Johnstoniana parva n. sp., a relatively small member of the genus, were reared. The species is described morphologically for all active instars (adult, deutonymph, larva). All stages appear to be restricted to wet places and live more or less concealed within the humid litter layer. J. parva is an univoltine species, but it is suggested that there are two oviposition periods: (1) After insemination in autumn, these eggs hibernate, diapausing within the substratum. (2) After hibernation in late spring, by females which have also been inseminated in autumn of the year before. Adults die soon after reproduction; males do not survive the winter. The larva emerges from June to August and is parasitic on parasitengonid mites, with a preference for those of other species of the same genus. After passing through the parasitic phase, individuals develop quite quickly to the adult instar within the same year. The active postlarval instars prey on diptera larvae and pupae. The data on parasitism and phenology is discussed with regard to habitat restriction of this species.