Scanning electron microscopy (SEM) was used to examine the external morphology of the head, legs, and postabdomen of adults of the Nearctic snailkilling fly Sepedon fuscipennis Loew (Diptera: Sciomyzidae). For both sexes, details are provided of the sensilla on the antenna, which has three sacculi on the first flagellomere. The number and arrangement of mechanosensilla on the aristae show sexual dimorphism. The black parafrontal spots are covered with microtrichia. Interfacetal mechanoreceptors were not numerous on the compound eyes, indication that sciomyzids are not major pollinators. Labellar hooks are evident in both sexes. A discussion is provided of various proposed functions. The shape of the head, especially the concave area housing the retractedmouthparts, suggests a novel explanation for the absence of a ptilinum in the genus Sepedon Latreille.