Examination of museum specimens, unpublished collection data, and field surveys conducted between 2010 and 2014 resulted in records for 22 species of sawflies new to Washington State, seven of which are likely to be pest problems in ornamental landscapes. These data highlight the continued range expansion of exotic species across North America. These new records also indicate that our collective knowledge of Pacific Northwest arthropod biodiversity and biogeography is underdeveloped, even for a relatively well known and species-poor group of insects. Notable gaps in the knowledge of Washington State’s Symphyta remain for the Olympic Peninsula, the Cascade Mountain Range, and the arid interior of the state. Washington’s shrub-steppe appears to be particularly poorly surveyed for sawflies.