Lethata asthenopa is a moth of the Depressariidae family. It is found in French Guiana. The wingspan is about 27 mm. The forewings are glossy purplish-brown with the costal edge light ochreous-rosy and the dorsal edge ferruginous-brown from one-third to the tornus. The plical stigma is dark fuscous and the second discal stigma is transverse, whitish and finely dark-edged. There is a very faintly indicated darker line from the middle of the costa to three-fifths of the dorsum, strongly curved outwards around the cell. A curved series of undefined blackish dots is found from three-fifths of the costa to four-fifths of the dorsum. The hindwings are grey.