We examined the scale of recruitment limitation in the western harvester ant, Pogonomyrmex occidentalis (Cresson). We measured colony density of 98 plots (0.25 ha) over an area of 500 ha. By applying an interpolation/extrapolation analysis to the spatial variability in colony density, we were able to accurately identify the location of two mating swarms. These two swarms were ≈1,400 m apart. Consequently, we conclude that if recruitment limitation generates variability in ecological processes such as density dependence, then variability should occur on the order of 1.5 km.