Archernis leucocosma is a moth in the Crambidae family. It was described by Turner in 1908. It is found in Australia, where it has been recorded Queensland. The wingspan is about 22 mm. The forewings are greyish-brown with a fine fuscous transverse line and a snow-white median discal spot, edged anteriorly with fuscous. There is a fine fuscous wavy line from the costa to the dorsum, edged posteriorly with white in the costal portion. The hindwings are greyish-brown with a snow-white discal spot edged anteriorly with fuscous. There is also a fuscous postmedian line, edged posteriorly with white throughout.