Thiotricha orthiastis is a moth of the Gelechiidae family. It was described by Meyrick in 1905. It is found in India (Punjab). The wingspan is about 13 mm. The forewings are dark fuscous with a broad ochreous-white streak occupying the costal half from the base, from the middle onwards gradually attenuated and leaving the costal edge, not quite reaching the apex. There is a fine white strigula between this and the apical fifth of the costa and there is a black apical mark. The hindwings are grey, darker posteriorly.