Baeomyia n.g. is described for a group of small (2–3 mm long) tachinids belonging to the Siphona group of the Siphonini. All known specimens were collected in western North America, with two species recorded from southern British Columbia (Baeomyia xanthogaster n. sp. and Baeomyia juniperi n. sp.) and three species recorded from desert localities in the American Southwest (type-species Baeomyia hurdi (Reinhard), Baeomyia antennata n. sp. and Baeomyia sonorensis n. sp.). Keys to adult males and females are provided for separation of species. Systematics of the Siphonini and Siphona group are reviewed, including a discussion of the synapomorphies upon which each is defined. Baeomyia species are inferred to form a monophyletic taxon within the Siphona group on the basis of five synapomorphies, though the relationship between the genus and other Siphona group taxa is unresolved. The apparent disjunction of Baeomyia species into northern and southern ranges may be the result of relatively recent speciation events, because differences among species are slight. A detailed zoogeographic analysis of the distribution pattern must await further phylogenetic data.