Invasive species management often focuses on the removal of dominant non-native flora, yet these interventions can unintentionally facilitate secondary invasions. This study evaluates the ecological consequences of removing the invasive shrub Rhamnus cathartica (common buckthorn) on the abundance of the invasive ant Myrmica rubra (European fire ant) and associated pollinator communities in a post-industrial preserve. Contrary to expectations, M. rubra abundance was higher in restored plots, a pattern linked more strongly to increased leaf litter thickness than to decreased canopy cover. Whereas cavity-nesting bee abundance increased following buckthorn removal, ground-nesting bees exhibited reduced abundance in areas with high M. rubra presence, suggesting direct or indirect antagonistic interactions. Diptera abundance also increased with restoration but remained unaffected by ant presence. These results underscore the potential for invasive species removal to create ecological conditions favorable to secondary invaders, thereby complicating restoration outcomes. The study emphasizes the need for integrated management approaches that anticipate secondary invasions and include ongoing monitoring to safeguard native biodiversity.