A normally uncommon but widespread Catocala throughout the northern Nearctic south of the boreal zone and into the western plains. The larva of parta is large, sleek, ranging from light steely gray to brownish gray in body color, with broken darker dorsal and lateral bands, A5 with small whitish bump, lateral filaments numerous and short. Venter with pinkish hue and dark spots on all segments. Head capsule without the conical vertex protrusions as in the otherwise similar amatrix (which also has a larger A5 bump and longer lateral filaments, and venter with orangish hue and either lacking or reduced dark spots beyond A5). Thick and well-defined dark black bars on edges of head capsule, often extending up and across the top of the head and even connecting at the midline suture (black bars in amatrix normally limited to edges). Recorded wild foodplants of parta include various Salix as well as Populus deltoides and Populus tremuloides.