As a result of comparative studying the ontogenesis of the Tydeid mites in the laboratory culture, a prelarva, dormant survival phase, binymphal development were found for the first time. This suggests the existence of three ways of adaptive reduction of ontogenesis within the family: embryonization of the early stages, omission of the intermediate ones and dropping of the final stages (juvenalization). The degree of expres¬sion of these processes varies in different representatives of the family and is, thus, an index of the level of adaptive reconstruction of the life form of Tydeids in the course of their evolutionary transition from the soil and litter to the higher plants. The develop¬mental phases of the Tydeid mites were homologized with the phases of initial cycle. The ontogenesis of Tydeids is interpreted as a limited epimorphosis and the family itself is considered as rather progressive, occupying an intermediate position between the pri¬mitive soil inhabitants and more specialized phytobionts.