Résumé : Gregarious arthropods are able to perform collective decision-making when having different options. In this study, we investigate how the sexual group composition and the geometry of the shelters influence the aggregation patterns of Periplaneta americana. We show that groups of males, groups of females and mixed groups composed of males and females have different interactions’ networks leading to different collective preferences in symmetrical (two horizontal or two vertical shelters) and asymmetrical (one vertical and one horizontal shelter) conditions that take their origin in the differences in the strengths of interattractions and in individual geotaxis preferences.