Two leaf-feeding beetles, Galerucella calmariensis L. and Galerucella pusilla Duft (Coleoptera:  Chrysomelidae), were released in 1992 as biological control agents for purple loosestrife, Lythrum salicaria L. (Lythraceae), in several states including Minnesota.  These two species were released in mixed colonies as they share similar niches in Europe.  As populations became established, it is unknown if both species continued to co-occur or if wetland type or climate might affect species abundance.  We proposed that post-release monitoring in Minnesota wetlands would provide insight into factors that affect the establishment of Galerucella spp.  In 2004 and 2005, approximately 60 and 80 wetlands, respectively, were sampled for Galerucella spp.  Species were determined by dissection of male genitalia.  Multiple sampling techniques, such as walk-through sampling and pheromone traps, were used to collect insects within wetlands.  Factors such as location, year of initial release, years a site was defoliated by beetles, wetland type, density of purple loosestrife, size of purple loosestrife infested area, and water level were used in a categorical analysis to determine if any of these factors are predictive of species composition.  Species composition sampling from Minnesota wetlands in 2004 indicated G. pusilla was more abundant (49% of wetlands sampled contained 90% or greater G. pusilla).  Galerucella pusilla-dominated wetlands were associated with continuous patches of purple loosestrife and permanently flooded wetlands located in the southern half of the state.  Post-release monitoring provides valuable information that can lead to improved efficiency and effectiveness of subsequent Galerucella spp. releases for controlling purple loosestrife.