Phyllonorycter lautella

Wingspan 6 to 7 mm. Adults are similar to a number of  and great care is needed with identification. The larvae mine the leaves of Oak. The mine is greater than 20 mm long, lower epidermis with one strong crease often dividing in Y-shape at end near leaf-margin. There can be several mines on a leaf.  The mines are often found on young seedlings and saplings.

The leaf mines on oak can be searched for from late autumn through winter, and it is relatively easy to rear the adult.  The species is difficult to identify from the mine alone, but can be identified in combination with the distinctive arrangements of hooks at the very end of the pupa, known as the 'cremaster'.  There is a key and description of these on Bladmineerders.nl here, and photos at https://mothdissection.co.uk/species.php?Tx=Phyllonorycter_lautella

Other oak Phyllonorycter species.

Adult mine/pupa

Adult: A clear set of photographs showing all critical identification features is required, and/or a voucher specimen may be necessary - check with the County Recorder before releasing the moth.  

Leafmine: Good photographs required and an indication of the length of the mine and the host species; also photograph the pupal cremaster.

Where young Oak seedlings and saplings are found.

There are two generations per year with adults on wing in May and again in August. Leafmines may be found in July, and during September and October, though much later by examining fallen leaves.

A local species that is widely distributed in the southern half of Britain. In the Butterfly Conservation's Microlepidoptera Report 2011 this species was classified as local.

Rarely recorded in Leicestershire and Rutland.

http://www.leafmines.co.uk/html/Lepidoptera/P.lautella.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/lepidoptera/ditrysia/gracillarioidea/gracillariidae/lithocolletinae/phyllonorycter/phyllonorycter-lautella/