The Argentine ant, Linepithema humile, is an invasive species that is prone to displacing native ant species. In this study, I investigated how a native species, Liometopum occidentale, was able to persist in an area of known Argentine ant invasion, in a location on the Stanford University campus in California. In particular, I measured foraging numbers on baits placed adjacent to existing trails of both species and baits placed in random locations within the ants' respective territories. I found that under the conditions of the study, L. occidentale foraged in much higher numbers than L. humile for both types of baits, though each species had comparable success in finding the baits. L. occidentale's foraging volume may be a safeguard against full invation by the Argentine ants, even if this advantage turns out to depend on the weather conditions.