Duponchelia adults have a wingspan of 19 to 21 mm. Their forewings are gray-brown in colour with two yellowish-white transverse lines. The outermost of these lines has a pronounced “finger” that points towards the back edge of the wing. When at rest the wings are held out from the body forming a triangle. The adult body measures 9-12mm in length. The head, antennae and body are olive brown. The abdomen has creat-coloured rings encircling it. The legs are pale brown.