The subfamily Pachygasterinae is here represented by five genera, Pachygaster, Neopachygaster, Eupachygaster, Zabrachia, and Berkshiria, containing 21 species, 13 of which are described as new: Zabrachia cornutum, Z. hebicornutum, Z. beameri, Z. microcephalum, Z. parvum, Z. albipilum, Z. lophum, Z. plicatum, Z. knowltoni, Neopachygaster occidentalis, Eupachygaster fusca, Pachygaster characta, and P. montana. This paper contains keys, descriptions, illustrations and biological information for the 21 North American species. New synonomies: Johnsonomyia aldrichi and Berkshiria aldrichi are synonyms of Berkshiria albistylum Johnson.