Wingspan c. 17mm.
A variable moth, some showing a distinct pale dorsal blotch and well defined markings, and others with a more obscure appearance. There is often a greenish or olive tinge to some of the markings.
This is a fairly common species throughout much of the British Isles where oak woodland is to be found. The adults fly in July and August and come to light.
The larva feed during May and June in folded or spun leaves of oak (Quercus).