Wingspan c. 6mm.
This is quite a local species, distributed mostly in the south-east of England.
The larvae mine the leaves of oak (Quercus), particularly Q. robur, and create a twisted gallery on the underside of the leaves, which sometimes combines to resemble a blotch. The feeding causes a 'green island' in the autumn leaves as they turn brown, and mines can often be found in fallen leaves as a result.
Adults are quite distinctively 'black and white' with three white patches on each wing, and a whitish fringe to the rear edge of the thorax. The head is usually blackish or dark brown, and the eycaps white.
Mines can be located in October and November, often many to a single leaf, with larvae still active in fallen leaves, and the moths are on the wing in June and July.