Pyrausta pseudonythesalis is a moth in the Crambidae family. It was described by Munroe in 1976. It is found in North America, where it has been recorded from California, Nevada, Arizona, New Mexico and Texas. The length of the forewings is 9–10 mm. The forewings are yellow with a dull red band across the terminal area. The postmedial line is reddish and the median area has a reddish wash or partial shading. The hindwings has a similar colour and pattern as the forewings.