AbstractHornets in the genus Vespa (Vespidae, Vespinae) are social wasps. They are primarily predators of other insects, and some species are known to attack and feed on honeybees (Apis mellifera L.), which makes them a serious threat to apiculture. Hornet species identification can be sometimes difficult because of the amount of intraspecific color and size variation. This has resulted in many species-level synonyms, scattered literature, and taxonomic keys only useful for local populations. We present a key to the world species, information on each species, as well as those intercepted at United States Ports of Entry during the last decade. Images of all the species and some of the subspecies previously described are also included.