We compared the density and diversity of ant colonies on areas where the vegetation had been altered by treatment with herbicides and on untreated areas. Highest densities of ant colonies were on the untreated mesquite dune habitat and the grassland habitat. The treated habitats were characterized by differences in shrub cover and composition and cover of forbs and grasses. Conomyrma bicolor and Solenopsis xyloni Were significantly more numerous on the mesquite dunes and grassland, respectively. The fungus-culturing ant, Trachymyrmex smithi, was abundant on the treated dune habitats and absent in the grassland habitat. Ant communities were most similar on the two sites subjected to vegetation modification, and most different comparing those dune habitats with the untreated mesquite dunes.