A comparative study was made of the stinging apparati of 102 species of aculeate Hymenoptera from the following families: Scoliidae, Vespidae. Eumenidae. Pompilidae, Sphecidae, Andrenidae, Halictidae, Megachilidae, Anthophoridae, and Apidae. Analysis was confined to the presence or absence of barbs: number, arrangement, and types of barbs. The sheaths were compared as to the types of setae and the presence or absence of segmentation.