From the seeds of two fruits of Cochlospermum vitifolium (Bixaceae) “poro-poro” we reared 47 individuals of Megacerus maculiventris Fahraeus, 1839 (Coleoptera: Bruchidae) (23 males, 24 females). In addition, we found the parasitoid wasp Stenocorse bruchivora (Crawford) (Hymenoptera: Braconidae: Doryctinae), one male and seven females, from larvae of the bruchid Megacerus maculiventris. The family Bixaceae, with the species Cochlospermum vitifolium, is reported for the first time as host plant of the genus Megacerus (Bruchidae). The percentage of damage caused to the seeds by the bruchid is reported.