Sideridis rivularis, the campion, is a species of moth of the family Noctuidae.

To the south, it is found in the Mediterranean Sea region (with the exception of Greece) and parts of Asia Minor.

Forewing brownish fuscous with a violet sheen; the lines double; claviform stigma large, black; orbicular and reniform grey with yellowish or whitish outlines, conversely oblique and contiguous on median vein; veins dark outlined with grey; submarginal line yellowish or white, dentate; hindwing brownish fuscous, darker in female: the ab.

has the outer half of costa of forewing pale; — S. mandarina Leech (now considered to be a species) from Japan and China, is rather larger and darker, the markings in consequence somewhat less distinct.

Larva greenish grey or yellowish, dotted with white: dorsal line dark with a row of oblique reddish grey stripes on each side.