Robber flies are one of the most dominant insect predators in desert grassland ecosystems. Habitat composition is temporally dynamic, with distinct seasonal plant phenologies resulting in unique fly assemblages. Habitat use by a particular species may narrow habitats of conservation priority to those with the highest species diversity or location of rare species. We are using malaise traps to assess robber fly habitat use through multiple years at a 12,000 acre site in Potter County, Texas. We will be sampling the four major macrohabitats found on the site: mesquite shrublands, grasslands, riparian corridors, and sand sagebrush prairies. However, data will only include flies collected in riparian and sand sage brush habitats during this initial year of sampling. Species composition and diversity will be compared between the two habitats, but preliminary analyses indicate that at least 10 species are found within both habitat types.