Understanding the mechanisms, by which climate and pollution affect animal population dynamics, is important for predicting population trajectories ofindividual species under different global change scenarios. We recorded population densities of different groups of herbivorous insects around two industrial pollution sources in the subarctic forests ofnorth-western Russia flom 1991 to 2018 and measured the impacts of natural enemies, host plant quality and temperature on the performance ofthese insects. Spring and autumn temperatures increased by 2.5-3 "C during the obseryation period, while emissions of sulfur dioxide and heavy metals decreased five-fold. Responses ofthe monitored insects to these environmental changes were variable due to the interplay between bottom-up and top-down effects, but only 2 of the 30 studied species showed the expected increase in density following climate warming. Our findings stress the importance oflong-term series in the global change research.