The larva of Metzneria aestivella feeds on the seeds of carline thistle. Occupied seed heads are not immediately obvious but often have a rather untidy appearance. Gently splitting them open will reveal feeding damage and the presence of a larva below the seeds.

The moth has been recorded on limestone grasslands in VC6. Carline thistle does occur in VC5 as well - I examined several plants at Hurlstone Point recently. I couldn't find the moth but these were very isolated. Perhaps it might occur elsewhere along the coast if it's more plentiful?