Cyclophora linearia, the clay triple-lines, is a moth of the family Geometridae.

The species was first described by Jacob Hübner in 1799 and it can be found in Europe and (primarily in the southern half) Britain.

On the forewing are three crosslines, black to reddish in colour, the middle is wider.

The egg is elongate-oval, with fine hexagonal or rather irregularly polygonal ribbing; pale yellow, becoming marked with red.

The larva is slender and naked, pale green, with small, yellow spots on the dorsum.