SUMMARY
Muscidae (Diptera) comprises one of the most important taxa in medical, veterinary and forensic entomology, especially due to their association with decomposing carcasses and cadavers. Yet, knowledge on their distribution and behaviour is still incipient in several biomes, which is the case of dry tropical forests. This study aimed to evaluate the attractiveness of different organic substrates to species of Muscidae in areas of seasonally dry forests (Caatinga) in Northern Brazil. Sampling was carried out in five Caatinga areas between 2015 and 2017, using suspended traps baited with bovine spleen, fish or human faeces. When all samplings were combined, 3,176 adults of nine species were collected. The assemblages of muscids had higher richness and abundances on bovine spleen, which attracted 66% of all specimens, when compared to the other substrates. Musca domestica was the most abundant species, and it was dominant in assemblages associated with spleen and fish. Assemblages attracted to spleen and fish had higher similarity, differing from those associated with faeces. Differences in food attractiveness are presented for species of medical interest as pathogen vectors (e.g., Synthesiomyia nudiseta (Wulp, 1883)) and of forensic relevance as colonizers of human corpses (e.g., Ophyra aenescens (Wiedemann, 1830)).