Field observations suggested that the harvester ant, Pogonomyrmex comanche (Hymenoptera, Formicidae), was the dominant ant in the prairie system of Todd Island in the Fort Worth Nature Preserve, Fort Worth, Texas. To begin testing this hypothesis, assessment of the ground active ant assemblage was made using pitfall traps beginning in March 2010 in two prairie habitats at the nature preserve. Preliminary assessment of the ant assemblage in March and April 2010 suggested weak support for seasonality of the ants with P. comanche not figuring prominently in any of the samples. However, beginning with the June sample, this picture changed dramatically with more species and more ants being collected. Here is presented the ant assemblage during the summer when ants are considered to be the most active. Bait stations were also used to examine dominance behaviors. The preliminary conclusion is that P. comanche is the dominant ant in this prairie system.