A few weeks ago I noticed this mine on Hawthorn by Dingestow Court Lake:
The rings of frass made me think of Leucoptera malifoliella, which had just one previous VC35 record, although they didn't look quite right. Today an incoming phone call while I was driving led to me parking by Jingle Street, and I noticed identical mines on several Hawthorn leaves by the car, accompanied by similar-looking mines with the upper surface creased like a Phyllonorycter. I collected several for checking and found that they match P. corylifoliella perfectly. This is a scarce Micro in Wales - there are just 5 previous Monmouthshire records - and is a species I have only seen once before as a mine. It's satisfying to know what these silvery mines with rings of black speckles are.
The same layby area held various other mines, including Cameraria on Horse Chestnut, Phyllonorycter acerifoliella on Field Maple, and a range of Stigmella species on Beech, Hazel and Hawthorn.