Satin Lutestring Tetheella fluctuosa
(Hübner, )Wingspan 35-38 mm.
The scarcest of the 'lutestrings' in Britain, occurring locally in scattered localities throughout England and Wales.
It prefers mature woodland and the larvae feed mainly on birch (Betula), but sometimes on alder (Alnus).
The adults fly from June to August and are attracted to light.