Metasia aphrarcha is a moth in the family Crambidae. It was described by Edward Meyrick in 1887.[1] It is found in Australia, where it has been recorded from Western Australia.
The wingspan is 16–19 mm. The forewings are light fuscous, becoming darker towards the basal two-thirds of the costa. The lines are irregular, cloudy and blackish. The first runs from one-fourth of the costa to one-third of the inner margin, the second from three-fourths of the costa to beneath the discal spot and then bent to the inner margin at three-fifths, preceded and followed by a white irroration (sprinkles), especially towards the costa. There is an indistinct dark fuscous dot beneath the costa before the middle and a small subquadrate discal spot obscurely outlined with cloudy blackish beyond the middle. There is also a hind marginal row of cloudy blackish dots. The hindwings are pale greyish ochreous, irregularly irrorated with fuscous. There is an obscure fuscous discal dot.[2]