Huebnerius dux is a species of moth of the family Noctuidae (owlet moths). It is found in Madagascar. The big head of this species is similar to the Sphingidae. Their antennae are light-brown and have 1/2 the length of the forewings.The abdomen is greyish-black, the forewings greyish black-brown. The hindwings are black-brown at their base with an edge of 1/5th of the wing in bright-yellow. Underside of wings is whitish grey-yellow.It has a wingspan of 100mm (male) to 107 mm (female). Saalmüller described this species from a couple from the collection of the museum of Lübeck.