Two sets of data on the distribution of Orthoptera over the plain parts of the Altai Territory are compared: one for the early 1920s, the other for 1999–2022. A total of 71 species and some members of 4 species groups that are hard to identify have been recorded in the study area. The distribution of some species, such as Bicolorana bicolor, Dociostaurus brevicollis, Stenobothrus lineatus, Omocestus haemorrhoidalis, Chorthippus apricarius, etc., across three natural subzones (southern forest-steppes, northern and typical steppes, and southern steppes) has not changed. Other species currently occur in the subzones where they were not recorded in the 1920s: the southern forest-steppes (Phaneroptera falcata, Tessellana vittata, Euchorthippus pulvinatus, Omocestus petraeus, Oedipoda miniata, etc.) or the southern steppes (Euthystira brachyptera, Omocestus viridulus, Myrmeleotettix maculatus, Chorthippus parallelus, etc.). Several species have become rare, and some of them (Asiotmethis jubatus, Notostaurus albicornis, Eremippus simplex, Gomphocerippus rufus, Sphingonotus coerulipes, etc.) are absent from our collections of 1999–2022. Thus, changes in the orthopteran distribution are differently directed or absent; therefore, they have resulted mainly from local transformation of ecosystems.
M. G. Sergeev (Mon,) studied this question.