''Tethea or'', the poplar lutestring, is a moth of the family Drepanidae. It was first described by Michael Denis and Ignaz Schiffermüller in 1775. The species can be found in Europe, northern and eastern Asia and Japan. The imago resembles ''Tethea ocularis''.
The wingspan is 38–43 mm. The moths flies from April to August depending on the location.
The larvae feed on willow and poplar, mainly ''Populus tremula''.