A new genus and species of tethinine flies from Kiptopeke, Virginia was discovered in the unsorted Diptera material in the National Museum of Natural History, Smithsonian Institution, Washington, DC. Delmarvatethina steineri new genus and species is herein described and discussed. New collecting records for three other tethinine flies, Tethina albula (Loew, 1869), T. willistoni (Melander, 1913), and T. parvula (Loew, 1869), from Delmarva are noted and a key to all four species is provided.