From 1995 to 2009, four Pseudacteon species were released in the U.S. with 3 species, P. curvatus, P. tricuspis, and P. obtusus released in Arkansas. To determine Pseudacteon establishment and expansion, sticky traps were used to monitor phorid fly species at and near 10 release sites, in counties bordering neighboring states, and along regional transects. Pseudacteon flies were captured in 16 Arkansas counties: Ashley, Chicot, Clark, Desha, Drew, Hempstead, Howard, Little River, Montgomery, Nevada, Perry, Phillips, Pike, Polk, Sevier, and Union. Pseudacteon curvatus was found in areas far from release sites, suggesting dispersal from neighboring states. The range of P. tricuspis evidently also expanded from its initial release sites in southern Arkansas.