The ants Aphaenogaster cockerelli and Pogonomyrmex barbatus compete for seed resources in the Chihuahuan desert. Previous work showed that intraspecific competition in P. barbatus is more intense between near neighbors with overlapping foraging ranges and depends on colony age. Just before reaching reproductive maturity (3–4 y), colonies are more aggressive and persistent in intraspecific competition for foraging area than younger or older colonies. In this study we examine how interspecific interference behavior by A. cockerelli towards P. barbatus depends on the age and proximity of P. barbatus colonies. Before sunrise when P. barbatus colonies become active, A. cockerelli colonies completely plug the nest entrances of some P. barbatus colonies, thereby delaying the onset of P. barbatus foraging behavior. Pogonomyrmex barbatus colonies closer to A. cockerelli were plugged more frequently than more distant colonies. As distance from A. cockerelli nests increased, older P. barbatus colonies were plugged more frequently than younger ones. Our results suggest that the intensity of interspecific interference competitive interactions may depend on the proximity and age of competing colonies.