The effect of the legume Mucuna deeringiana on Cosmopolites sordidus population dynamics and damage was studied in two planting systems: intercropping with mucuna and mucuna as green mulch before establishing the plantain. The relationship between C. sordidus adult density and larval damage was also studied. The presence of M. deeringiana affected the incidence of C. sordidus.The data suggest that C. sordidus adults are attracted by M. deeringiana, but additional studies are needed to better understand the relationship between the legume and the insect. The presence of M. deeringiana did not affect plantain height, stem diameter, or sucker production if the legume was eliminated four months after planting. However, management practices to establish and cultivate the legume increased production costs. Although C. sordidus population densities were low during most of the year, a high population density was recorded from November to January. A second population explosion was recorded between June and August. The highest insect density recorded was 3.5 insects per trap.