A medium-size (approx. 3.0 – 3.2 cm. wingspan) olive green moth with black and white lines and spots. The antemedian and postmedian lines are very erratic, black lined with white scales. The orbicular and reniform spots are prominent, white with green filling and partially ringed with black. The fringes are checkered green, black and white. The hindwings are light black, with some pale scaling along the upper edge and a pale fringe. Sexes are similar, but males have narrowly bipectinate antenna, females simple. Feralia jocosa can usually be separated from other Alberta Feralia by the combination of small size, dark hindwings, and the lack of blocks or large patches of black scales on the forewings. Occasional specimens have some or all the olive green replaced with yellow-brown. Adults and the genitalia of both sexes are illustrated by Poole (1995).