Syllepte tetrathyralis is a moth in the Crambidae family. It was described by Hampson in 1912. It is found in New Guinea. The wingspan is about 26 mm. The forewings are orange-yellow, the medial area suffused with fulvous except the costal area and the inner margin. The costal edge is black and there is a hyaline spot from the middle of the cell to above vein 1, connected with a hyaline point beyond it in the cell. There is a yellow point at the upper angle of the cell and a hyaline spot beyond. There is also an indistinct diffused waved subterminal line. The hindwings are orange-yellow with some fulvous suffusion on the basal inner area. There is a small dark brown mark on the median nervure near the base followed by a hyaline patch from the middle of the cell to the submedian fold, then