Bucculatrix thoracella

Wingspan 6 to 8 mm. A tiny but easily distinguished species, showing large brown patches on a yellow ground colour and a narrow brown streak extending into the cilia.  The larva mines the leaves of Lime, creating a small hook-shaped mine; later instars feed freely on the leaves.

Adult Leafmine

Larval stages: Photograph backlit mine, note host species in comments

It is associated with Small-leaved Lime and sometimes Common Lime.

The moths fly in June, and sometimes again in August in the south.

The larvae mine the leaves of its host trees at first, and then create small feeding windows.

Fairly frequent. In the Butterfly Conservation's Microlepidoptera Report 2011 this species was classified as common.

It appears to be uncommon in Leicestershire and Rutland, where there are few records. L&R Moth Group status = D (rare or rarely recorded).

http://www.leafmines.co.uk/html/Lepidoptera/B.thoracella11.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/lepidoptera/ditrysia/gracillarioidea/bucculatricidae/bucculatrix/bucculatrix-thoracella/