BIONATURE

Butterflies and dragonflies are among the most widely observed insect groups used to interpret environmental change, yet their indicator value is sometimes asserted more confidently than the evidence permits. This critical narrative review examines how butterflies, dragonflies and damselflies function as ecological barometers across terrestrial, freshwater and connected land–water systems. Butterflies are especially informative where environmental change alters terrestrial habitat quality, host-plant availability, nectar continuity, microclimate, phenology, agricultural intensity and pesticide exposure. Dragonflies and damselflies, by contrast, integrate aquatic larval conditions with adult use of riparian and terrestrial habitat, making them useful indicators of wetland integrity, stream condition, hydrological alteration, riparian degradation and climate-driven freshwater change. The central argument is that these taxa are most valuable when treated as complementary sentinels rather than interchangeable proxies for insect biodiversity. Their strengths arise from short generation times, ectothermy, strong habitat associations, visual detectability and, in some regions, well-developed monitoring traditions. Their limitations arise from uneven detectability, biased geographic coverage, taxonomic and functional heterogeneity, lagged responses, dispersal-mediated rescue effects and the difficulty of attributing biological change to single drivers. Evidence from long-term monitoring, community science, trait-based analysis, biotic indices and distribution modelling shows that both groups can register climate warming, land-use intensification, pollution and restoration. However, the signal depends on life stage, species traits, landscape context and sampling design. Butterflies and dragonflies should therefore be embedded in multi-taxon, repeated and transparent monitoring programmes that combine abundance, occupancy, traits, phenology, breeding evidence and environmental covariates. Used in this way, they can support earlier detection of ecological change, guide habitat restoration and strengthen the accountability of biodiversity policy without reducing complex environmental change to a single charismatic indicator group.