Cosmorhoe ocellata, the purple bar, is a moth of the family Geometridae. The species can be found in the Palearctic ecozone, which includes Western and Central Europe including the British Isles, Central Asia, Asia minor and Kyrgyzstan. The moths fly from May to August. . The larvae feed on various types of bedstraw. In the Alps, it can be found at altitudes up to 1500 meters.The species is found in many different habitats, including deciduous and mixed forests and heath, bushy places, and park-like landscapes