Stigmella oriastra is a moth of the Nepticulidae family. It is found in New Zealand. The length of the forewings is about 3 mm. Adults have been recorded in January and from October to December. There is probably one generation per year. The larvae feed on Celmisia species, including Celmisia coriacea. They mine the leaves of their host plant. The mine consists of a narrow gallery, initially in a circular pattern and later linear. The frass is deposited in the middle of the mine. Larva have been recorded in February, April and May. They are 3–4 mm long and pale yellow.