Wingspan 8 to10mm. The larvae of this species mine the leaves of Oak species. They characteristically make twisting initial mines in the upper epidermis, which then join to form a large blotch, with a silvery appearance.

Adult Leafmine

In open woodland and other areas where the host species occur.

The moth is univoltine, being in flight at the end of July. It can also overwinter and be found again in April and May.

The larvae feed on Oak (Quercus spp.) 

This is a very local species, occurring mainly in southern England and southern Ireland. Occasional sporadic populations are to be found further north. In the Butterfly Conservation's Microlepidoptera Report 2011 this species was classified as local.

Previously considered quite rare in Leicestershire and Rutland, the increase in leafmine recording in VC55 has shown it to be a litttle more frequent than previously thought.

http://www.leafmines.co.uk/html/Lepidoptera/A.brongniardella.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/lepidoptera/ditrysia/gracillarioidea/gracillariidae/gracillariinae/acrocercops/acrocercops-brongniardella/