Elachista gerasmia is a species of moth of the family Elachistidae that is found in New Zealand and south eastern Australia.[1] [2]
This species was first described by Edward Meyrick in 1889 from specimens collected in Hamilton, Makatoku in Hawkes Bay and in Invercargill.[3] The male lectotype, collected in Hamilton, is held at the Natural History Museum, London.
The wingspan is 9–14 mm. The forewings are light grey or sometimes grey-whitish. There is a black dot on the fold in the middle, and an elongate black dot in the disc at two-thirds. The hindwings are grey.
This species is found in both the North and South Islands of New Zealand as well as in Queensland, New South Wales, South Australia and Tasmania.[4]
Elachista gerasmia inhabits damp swampy habitat. The larvae of this species are leaf miners.[5] Larval hosts include plant species in the genus Juncus including Juncus australis, Juncus pallidus and Juncus usitatus.