Tachina fera and Tachina magnicornis are two very similar, large, bristly parasitic flies that are difficult to distinguish from one another. T. fera is more common and widespread, while T. magnicornis is a recent arrival in some areas. Key differences often cited include the abdomen's dorsal stripe ending in a point (T. fera) versus a lozenge shape (T. magnicornis), but these can be variable.