Contrasting light environments in rainforests generates changes in the characteristics of the leaves and in the herbivore community. In the present study, we carried out a reciprocal transplant experiment under natural conditions to determine the plasticity of leaf characteristics of plant species that grow in contrasting light environments in a Neotropical forest. We further explored the relationship between these traits and insect herbivory. We found that six woody species differ markedly in the phenotypic plasticity of leaf features. The specific leaf area, chlorophyll content, carbon content, nitrogen content, and leaf thickness of the most light-demanding species were highest in gaps, but their carbon/nitrogen ratios were higher under closed canopies. The herbivores were more abundant in gaps (5.9%–14.8%) than under closed canopy habitats (3.4%–6.1%) and seemingly associated to the plasticity of the leaf traits. We observed 47% more herbivores in gaps than under closed canopies. Our results suggest that the phenotypic plasticity of leaf traits depends on the identity of the plant species and its wood density, while herbivory seems to be affected by plant defence, low nutritional quality, or herbivore tolerance.