The article presents materials on 45 species of Lepidoptera of 14 families, collected by the authors during fieldwork in the northeast of the Russian Plain, the Subpolar and Polar Urals in 2013–2025. For the territory of the Komi Republic, Kirov and Arkhangelsk Oblasts, Perm Krai, Nenets Autonomous Okrug, and Yamalo-Nenets Autonomous Okrug, species encountered for the first time and locations of new species records are indicated, along with the names of localities, geographical coordinates, and the amount of the collected material. The species essays contain the authors’ comments on shifts in the range boundaries, suggestions regarding the probable reasons for the rapid dispersal and naturalization of adventive species, and description of the identified features of their distribution among landscapes and biotopes, life cycle, phenology, and trophic relationships in the new territories. It is concluded that the main pathways for the dispersal of Lepidoptera species from southerner regions are mainly associated with linear infrastructure, such as highways, railways, power lines, oil and gas pipelines, which, together with river valleys, act as quasi-natural corridors. The successful and rapid naturalization of adventive species is facilitated by the anthropogenic transformation of natural ecosystems through industrial-scale logging, mining, road construction, and urbanization. These processes significantly expand the area of suitable habitats for Lepidoptera, serving as stepping stones where they can get established. It is predicted that the penetration and naturalization of adventive species in the northeast of the Russian Plain and in northern regions of the Urals will be gaining pace, which will inevitably affect the species composition of local and zonal faunas, ultimately leading to a transformation of the spatial and typological structure of the population, and possible displacement and reduction in the numbers of native Lepidoptera species.