In temperate areas, microclimate is a key factor affecting the population dynamics of insects, but very few studies have examined the potential significance of microclimate in diverse tropical insect communities. We quantified the diversity and structure of butterfly communities in 2 different microhabitats, over seasons, and examined which abiotic (microclimate) and biotic (vegetation structure) components affected community composition. The study was performed from Jun 2009 to May 2010 at a dry forest in Ecuador, a globally threatened habitat with high levels of endemism. Two transects were established, one in each microhabitat, where baited traps were located in the understory and canopy to record butterfly species abundance. Humidity and temperature were recorded during the sampling period and vegetation variables were measured. A total of 3,731 individuals representing 93 species were collected. Higher species richness and abundances were found during the wet season. Linear regression models and CCA analyses showed microclimatic variability and vegetation structure (e.g., vegetation density) were significant predictors of the composition and abundance of butterfly communities. Major lineages of butterflies differed in their response to microclimate and microhabitat, explaining some of the spatial variation in community structure. In addition, some of the most abundant species changed their microhabitat preferences in the dry season. The tight relationship between butterfly communities, microclimate and microhabitat suggests that global climate change and habitat alteration are likely to act synergistically on tropical dry forest insect faunas, and these processes should thus be considered together in predicting future impacts on biodiversity.