In arid zones the structure of assemblages of granivorous organisms is frequently influenced by competitiva interactions. In this study we analize some community attributes related to the use of seed baits byharvester and species from five Chilean localities along a precipitation gradient. In addition, we describe thedaily activity of species.No more than three ant species were detected by locality, this result may be due to the low species richnessof harvester ants in Chile. However, in three of the five studied localities, the overlap in seed bait utilizationwas less than expected by chance, being generally more frequent at temperature below 35°C. The low overlapin bait utilization might be adscribed, in principie, to the high territoriality of Solenopsis gayi.