Eudonia legnota is a moth in the Crambidae family. It was described by Meyrick in 1885. It is found in New Zealand. The wingspan is 18–23 mm. The forewings are pale brownish-ochreous, irrorated with dark fuscous or blackish on the veins. The first line is white, suffused with whitish anteriorly and margined with dark posteriorly. The second line is white and there is a hindmarginal row of black dots. The hindwings are ochreous-grey-whitish. Adults have been recorded on wing in December and January.