Horace’s Duskywing has a wingspan of 1.25 to 1.75 inches. The male’s forewing dorsally is dark brown with no contrasting pattern and small translucent spots. The female’s forewing dorsally is light brown with contrasting dark pattern and larger translucent spots. The hindwings are mottled light and dark brown. The male has a costal fold along the leading edge of the forewing with yellow scent scales. After May (when Juvenal’s Duskywing is no longer flying) Horace’s is the only duskywing flying that has a white spot at the end of the forewing cell. The caterpillar is gray green sprinkled all over with white speckles. The head is rusty brown.