John Carr wrote:
A useful character to check, no matter what key you use, is the strength of the pre-alar (first postsutural supra-alar) bristle. If it is clearly stronger than the dorsocentrals and notopleurals, and the antennae are of normal form, you most likely have what has been called the "vast central mass" of Tachinidae: the Goniini and Eryciini, which are externally indistinguishable. (Maybe the Ethillini too; they are quite rare in America.) The Tachinini have a strong pre-alar but different antennae.