Factors affecting local geographic distribution, foraging behavior and activity, forage selection, numbers of foragers per colony, nest spacing and nest structure of Pogonomyrmex rugosus and Pogonomyrmex barbatus were studied. There were seasonal differences in foraging activity. P. barbatus was more active in early summer and foraged at night while P. rugosus was more active in mid-summer foraging at night during July. Both species exhibited forage preference for grass seeds but took a variety of other materials. Where both species inhabited the same area they had an index of overlap for forage of 0.7. The colonies of both species were randomly distributed. Colony density was approximately 20 per hectare in areas supporting one or both species. There was no evidence of intraspecific aggression and foraging areas of colonies of the same species overlapped considerably. P. barbatus and P. rugosus avoid competition by habitat selection. Interspecific aggression probably accounts for the lack of overlap in local distribution.