Wingspan 6-8 mm.
The larva of this species feeds on oak, initially mining the twig, later entering the base of the leaf through the midrib.
When almost fully fed, the larva cuts out a small area from the leaf base to create an oval case, in which to descend to the ground and pupate.
The adult moths emerge in May, and may be found in numbers around the foodplant during the day, throughout much of Britain.
Leafmine (British Leaf Mining Fauna)