Large for a Photinus
. Blackish-brown finely, densely rugose (wrinkled) elytra, side margins and suture of elytra yellow. Pronotal disk pinkish with a black spot. Pronotum convex. Underside: Ventral abdominal segments six and seven large and occupied by light organ in male. Abdominal sternites of male have distinct (2)
. Female flightless (3)
, or "seldom" flies, as it does have normal wings (4)
Flash is distinctive: male hovers about two feet (0.6 m) above ground, then drops vertically, gives single prolonged flash as is ascending, then flash diminishes (2)
. Flashing occurs at dusk, earlier in evening than most other fireflies.