This dataset supports the manuscript entitled: “Ecological constraints affecting population dynamics of the pine processionary moth at the southern edge of its range.” The data derive from a 10-year monitoring program (2015–2024) conducted across three forest ecosystems in northern Algeria (coastal, inland, and mountain sites). The study investigates spatial and temporal variability in population density of the pine processionary moth (Thaumetopoea pityocampa) and evaluates the relative contribution of density-dependent regulation and climatic constraints.