Carrion provides a multifaceted model to investigate basic and applied aspects of insect ecology and behavior. In this study, we analyzed differences in the attractiveness and suitability of vertebrate carcasses to sarcosaprophagous species of Diptera (Calliphoridae, Sarcophagidae, Muscidae, and Fanniidae). Carcasses of fish and rat were used as substrates in a fragment of rainforest in Northeastern Brazil. The diversity of adults that visited the carcass was compared with the diversity of species that effectively used them as substrates for the development of larvae (colonizers). All insects were collected daily until complete skeletonization of the carcasses. Insects of at least 31 species were attracted to the carcasses, of which Chrysomya albiceps (Wiedemann, 1819) and Chrysomya megacephala (F., 1794) were the most abundant. Only nine species effectively colonized the substrates, as evidenced by the emergence of colonizers. Most species did not discriminate between the carcass as visiting adults and as colonizers. A higher species richness and abundance of dipterans occurred in the intermediate stages of decomposition. The exotic Chrysomya species outcompeted native species in terms of abundance and dominance on both carcasses. Although Calliphoridae dominated the assemblage of visitors, species of Fanniidae were, proportionally, the most effective colonizers, when abundance was taken into account. Blow flies emerged earlier than species of Fanniidae and Sarcophagidae, which completed their development 19 d postcollection. The results contribute to understand the dynamics of carrion colonization and provide further evidences on the potential of necrophagous insects for forensic entomology.