The gall-forming Lipara orientalis Nartshuk, 1977, stat. n., described as a subspecies of L. rufitarsis Loew, 1858 from Mongolia, was reared on the common reed, Phragmites australis, in two localities of Altai (the vicinity of Bijsk City and Savushka village, 11 km NW Zmeinogorsk). The specific diet of L. orientalis in gall and the various larval structure shapes showed strong differences from L. rufitarsis Loew and confirmed its status as a good species. It was shown that the parasite of L. orientalis larvae in galls is Baryproctus barypus (Marshall, 1885) (Hymenoptera, Braconidae). Cryptonevra flavitarsis (Meigen, 1830) and C. consimilis (Collin, 1932) (Diptera, Chloropidae) are developed as inquilines, and the former species prevailed over the latter in collected galls. Cryptonevra consimilis (Chloropidae); Cryptonevra flavitarsis (Chloropidae); Lipara orientalis Nartshuk 1977 (Chloropidae): Diagnostic characters, P. 112, Host, Parasite; Lipara rufitarsis Loew 1858 (Chloropidae): Diagnostic characters, P. 112; Lipara rufitarsis orientalis Nartshuk 1977 (Chloropidae): Raised to, Lipara orientalis, p. 111; Baryproctus barypus (Braconidae): Parasite. Russian none