Mites of the family Tarsonemidae are widespread in ecosystems, inhabiting various substrate types and exhibiting diverse trophic preferences. Representatives of the genus Steneotarsonemus are phytophages, while the majority of representatives of the genus Tarsonemus are mycophages. The aim of this study was to assess the dynamics of the species composition of tarsonemid mites in the phytocenosis of the wild grass Bromus inermis during the growing season. Sampling was conducted monthly from June to November 2025 in a homogeneous meadow ecosystem near Tyumen, Western Siberia. On each sampling date, one sample was formed from each type of substrate: seven panicles, seven stems, litter and soil. Each substrate type was placed into a Tullgren funnel for mite extraction. The obtained numbers were recalculated per one panicle, stem and square meter, respectively. All collected tarsonemid mites were identified to species level. A total of 7 species of tarsonemid mites were found, belonging to two trophic groups: mycophages (Tarsonemus violae, T. virgineus, T. confusus, T. annotatus, T. waitei) and phytophages (Steneotarsonemus (s. str.) arcuatus, S. (Steneotarsonemoides) sp.). On Bromus inermis panicles in June, S. arcuatus dominated. All developmental stages were present during this month, mainly larvae (133 specimens per panicle), adult females (94 specimens), and males (8 specimens). According to our observations, by early August, this species had left the panicles and moved into the soil. During this period, females of T. violae (39 specimens) ascended to the panicles, and an increase in their abundance was recorded until the end of November. In the soil in June, mycophagous tarsonemids dominated: T. virgineus (5039 specimens/m²), T. annotatus (2160 specimens/m²). From July to the end of November, S. arcuatus dominated (36,344 specimens/m²). In the litter, T. virgineus dominated in July (1047 specimens/m²), S. arcuatus in August (15,845 specimens/m²), and from September to the end of November, T. violae dominated (1020 specimens/m²). A similar situation was observed on Bromus inermis stems, where S. arcuatus females dominated in July (35 specimens per stem), then moved into the soil, and from August onwards, an increase in the abundance of T. violae was recorded, reaching 45 specimens per stem by the end of November. Thus, during the growing season, a succession of the tarsonemid mite community occurred, shifting from mycophages to phytophages in the soil, and from phytophages to mycophages on Bromus inermis plants. The present research was supported by the Russian Science Foundation, grant No. 25-14-00118.