The length of the forewings (either of the two front wings of a six-winged insect) of a Tridrepana subadelpha, which are pale yellow with a brown crescent patch under the apex, with a brownish-black ovate spot inside, is about 13 mm.
The length of the forewings is about 13 mm. The forewings are pale yellow with a brown crescent patch under the apex, with a brownish-black ovate spot inside. 
