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A medium-size moth (approx. 3.5 – 3.8 cm wingspan) with dark, almost black, red-brown forewings and lighter brown hindwings. Forewing markings consist of a light yellowish doubled curved antemedial line and a faint almost obsolete dark postmedian line. The area basad of the antemedial line is usually partially filled with light brown or yellowish scales. The small orbicular spot and larger reniform spot are only slightly lighter than the ground, and are preceded and separated by jet black in the cell. The subterminal line is indicated by a few pale scales, in particular where it approaches the lower margin. The most prominent marking is a pale yellowish or pale pink diffuse blotch on the costa just distad of the reniform spot, from which it gets its common name. Most similar to P. tenuicula, which it differs from in the curved antemedial line (straight in tenuicula) and by the pale yellowish or pinkish blotch on the costa just distad of the reniform spot (absent in tenuicula). Bicarnea is also noticeably larger and broader-winged than tenuicula.

The larval hosts are in part uncertain; Crumb (1956) listed a variety of plants in several families, including blueberry, Gray birch, dandelion and Spiraea. However, McCabe (1991) found the larvae would only feed on two species of grass (Glyceria maxima (Hartm.) Holmb. and G. canadaensis (Michx.) and rejected blueberry, Grey birch, raspberry, yarrow, nettle, dogbane and elder.

An eastern species, found from NS west to central southern Alberta, south to ND and KY. In Alberta it has been collected in the Red Deer River valley at the Tolman Bridge Recreation Area, and in the dunes southeast of Wainwright.