The wingspan is 18–20 mm. The forewings are blackish-fuscous, irrorated with white. Both the first and second line are white. The hindwings are grey. Adults have been recorded on wing in December. As a result of further study of the male genitalia, it has been argued that this species should be placed in the genus Eudonia. Based on this as well as the wing pattern, it has also be postulated that S. illotabelongs to the same species as ''Eudonia pachyerga.''
Distribution
This species is endemic to New Zealand. It is found in the forests of southern New Zealand. It is locally common in Thomsons Bush in Invercargill as well on the Cascade Road in South Westland.
Life stages
This species' larvae are leaf miners. They form silk tunnels amongst the leaves of their host plants.