Herbivory has been identified as a potent evolutionary force, but its ecological impacts have been frequently underestimated. Leaf-cutting ants represent one of the most important herbivores of the Neotropics and offer an interesting opportunity to address the role played by herbivorous insects through a perspective that embraces population- to ecosystem-level effects. Here we: (1) qualitatively summarize the multiple ways leaf-cutting ants interact with food plants and their habitats and elucidate the ultimate outcome of such interactions at multiple organization levels; (2) update our understanding of leaf-cutting ant-promoted disturbance regimes; and (3) examine potential ecological roles by leaf-cutting ants within the context of human-modified landscapes to guide future research agendas. First, we find that leaf-cutting ants show that some herbivorous insects are able to generate ecologically important disturbance regimes via non-trophic activities. Second, impacts of leaf-cutting ants can be observed at multiple spatio-temporal scales and levels of biological organization. Third, ecosystem-level effects from leaf-cutting ants are ecosystem engineering capable not only of altering the abundance of other organisms, but also the successional trajectory of vegetation. Finally, effects of leaf-cutting ants are context-dependent, species-specific, and synergistically modulated by anthropogenic interferences. Future research should examine how leaf-cutting ants respond to deforestation and influence remaining vegetation in human-modified landscapes. By promoting either heterogeneity or homogeneity, leaf-cutting ants operate not only as agricultural pests but also as ecological key players.