Elachista napaea is a moth in the Elachistidae family. It was described by Philpot in 1930. It is found in New Zealand. The wingspan is 9-10 mm. Head and thorax grey. The forewings are whitish-grey with a few ochreous and various blackish scales. There is a series of blackish dots along the fold from near the base to about one-third and an ochreous blotch on the fold at about three-fourths, containing a linear black mark. The hindwings are fuscous-grey.