Homalinotus validus is an important pest of babassu palm (Attalea speciosa) cultures in North Brazil. Investigations on the chemical ecology of this species are essential for the development of an integrated pest management system, since attempts to control the pest by conventional insecticides failed. GC/MS and GC/FT-IR analyses of headspace volatiles obtained from males and females revealed the presence of two male specific compounds, which were identified to be (1R,2S)-grandisol and the new (1R,2S)-grandisyl acetate. Both compounds presumably act as an aggregation pheromone of the species.