Technical Abstract: Classical biological control efforts against the imported fire ants have largely involved the use of Pseudacteon parasitoids. To facilitate further exploration for species and population biotypes we organized a database of collection records for Pseudacteon species, including those from the literature and other sources. These data were then used to map the geographical ranges of species associated with the imported fire ants in their native range in South America. In addition, we found geographical range metrics for all species in the genus and related these metrics to latitude and host use. Approximately equal numbers of Pseudacteon species were found in temperate and tropical regions, though the majority of taxa found only in temperate areas were found in the Northern Hemisphere. No significant differences in sizes of geographical ranges were found between Pseudacteon associated with the different host complexes of the fire ants despite the much larger and systemic collection effort associated with the S. saevissima host group. Geographical range of the flies was loosely associated with both the number of hosts and the geographical range of their hosts. Pseudacteon with the most extensive ranges had either multiple hosts or hosts with broad distributions. Mean species richnesses of Pseudacteon in locality species assemblages associated with S. saevissima complex ants was 2.8 species, but intensively sampled locations were usually higher. We discuss possible factors related to variation in geographical range size and outline areas in southern South America that have likely been under-explored for Pseudacteon associated with imported fire ants.