Thiotricha argyrea is a moth of the Gelechiidae family. It was described by Turner in 1919. It is found in Australia, where it has been recorded from Queensland. The wingspan is about 12 mm. The forewings are shining-white with three suffused grey dorsal blotches, sub-basal, median and tornal. There is a short oblique grey streak from five-sixths of the costa, succeeded by a narrow parallel blackish streak. There is also a blackish apical dot. The hindwings are grey.