The Lunar Thorn (Selenia lunularia) is a moth of the family Geometridae. It is found in Europe.
The wingspan is 38–44 mm. The length of the forewings is 16–22 mm. The moth flies in two generation from mid-May to mid-August .
The caterpillars feed on various deciduous trees, such as birch and oak.
- ^ The flight season refers to Belgium and The Netherlands. This may vary in other parts of the range.