Cassida denticollis is a species of beetle in the leaf beetle family, that can be found in Mongolia, West China (Xinjiang province), and the Western Palaearctic region. The species feeds on plants from the Asteraceae family, including Achillea millefolium, Artemisia absinthium, Artemisia campestris and various plants Tanacetum species, including Tanacetum corymbosum and Tansy.