This paper describes the morphology and histology of the adult digestive system of Cephalodesmius armiger Westwood (Scarabaeini), a beetle that manufactures compost out of plant matter. This species' digestive system is compared to those of genera Phanaeus, Coprophanaeus and Copris (Coprini), that feed on vertebrate dung. The major finding reported in this study is that C. armiger has a sac-like colon, a structure similar to the fermentation chamber of phytophagous beetles, not found in other Scarabaeinae.