A diverse sawfly fauna of 176 species in 66 genera in 10 families occurred in three parks in the George Washington Memorial Parkway – Dyke Marsh Wildlife Preserve (DMWP), Great Falls Park (GFP), and Turkey Run Park (TRP). Adult sawflies flew from early March through mid-November. They included the rarely-collected Kerita fidala Ross, a leafminer of Mertensia virginica (L.) Pers. ex Link (Boraginaceae) and an unidentified Caliroa sp. which consumes Staphylea trifolia L. (Staphyleaceae). Nine of the collected species are alien ones in North America. Based on coefficients of community, DMWP was more similar to TRP than GFP, and GFP and TRP were more similar to one another than to DMWP. In DMWP, most species were uncommon in samples. Ninety-five percent of the reported host genera of the collected sawfly species occurred in all three of the parks.