Colonies of the western harvester ant (Pogonomyrmex occidentalis Cresson) with greater genetic diversity begin foraging earlier, forage for longer durations, and collect more food than those with less genetic diversity. In this study we tested whether earlier onset of foraging improved the foraging success of colonies at baits placed midway between neighbors. Colonies that began foraging earlier in the morning were more likely to be the first to discover the food and to monopolize the food source. Colony size was also important with larger nests monopolizing significantly more baits than smaller nests. These results show that early foraging by colonies can provide an intraspecific foraging advantage at a clumped food resource. This advantage adds more evidence to a growing body of work showing how polyandry, genetic diversity, and colony-level performance are interrelated in P. occidentalis colonies.