In April 2003, we conducted a statewide survey of Solenopsis invicta (Buren) populations to determine the pathogens infecting this insect in Louisiana. The ultimate goals were to establish baseline data for S. invicta pathogens, analyze associated environmental data for factors that might affect prevalence, and identify pathogens with potential for being developed as biological control agents. In all, we surveyed 165 sites (1804 colonies) ranging from lawns in residential neighborhoods, to highway right-of-ways, to agricultural fields. At each site, we established a 0.05 ha plot, determined the density and size of S. invicta colonies, and collected ant samples from a maximum of 10 colonies. We also collected soil and vegetation samples at each site. In the laboratory, the ant samples were first observed for gross symptoms of disease. This was followed by microscropic examinations of wet mounts and trichrome stains of ant smears. Finally, the samples were screened with the polymerase chain reaction with disease-specific primers. Here, we present the results of our survey with respect to the occurrence and distribution of the microsporidium Thelohania solenopsae (Knell, Allen and Hazard). Overall, T. solenopsae was detected at 25 sites; 12 were loosely concentrated in east central Louisiana, and 5 in the south west. The remaining 8 sites were scattered across the state. Eight of the positive sites had 90-100% infection among colonies. All four infection x social form possibilities were detected: uninfected polygyne, infected polygyne, uninfected monogyne, and infected monogyne colonies.