Hybrid community theory explains that interaction diversity matters for the stable coexistence of multiple species. However, it remains unclear how an ontogenetic change in interaction type mediates community dynamics, despite its ubiquity in nature and in plant-insect interactions in particular. The most representative example is the metamorphosis of pollinating insects in which larvae are herbivores. In this study, we develop a minimum stage-structured community module in which juveniles exploit a resource while adults act as mutualists of another one. We then compare the stability of the structured hybrid community module with that of the corresponding trophic module in which both stages are antagonistic. We show that the ontogenetic antagonism-mutualism coupling is stabilizing in that it increases the consumer persistence in poor environments while improving the community resilience in productive environments. Further, these stabilizing effects are robust to whether interactions are linear or nonlinear. Considering that insects and plants the most diverse lineages, our results suggest that the ontogenetic antagonistic-mutualistic coupling may play an important role in maintaining their great biodiversity in fluctuating environments.