From the upper Great Plains through the Rocky Mountains and western Nearctic, there are 13 species of large Catocala that feed on willows and poplars, and whose larvae are quite similar, have parallel extents of variability, and overlap at least in part on the morphological characters examined to date. But as a group these 13 are recognizable -- many thin, linear and usually long lateral filaments; cream to tan to light brownish gray body color (some strongly patchily maculated darker morphs also occur); A5 saddle patch more darkly maculated than ground color, with dorsolateral through dorsoventral bands typically prominent only on A5; low transverse A5 bump, often more lightly colored on top; head capsule color usually comparable to body color, with modest protruding lobes with lighter ochre to orange accents and indistinct netlike lobe to frons striping; varyingly thickened black lateral line from vertex normally to above ocelli, and extending over capsule top; black venter spots throughout segments notably around A2-A5; venter color off-white and sometimes with mauve/pink overtone. The culprits include babayaga, briseis, californica, cleopatra, faustina, grotiana, hippolyta, irene, jessica, junctura, luciana, meskei and semirelicta. In many regions the choice can be narrowed to only a couple species. However, because (a) the extent of infrapopulational and geographic pattern variation both remain poorly known, and (b) their respective larval foodplant preferences among Populus and Salix are likewise incompletely understood, it is typically dicey to assert species identity for most wild larvae with confidence in the absence of a reared adult.