The tansy beetle (Chrysolina graminis) is a species of leaf beetle. It measures 7.7–10.5 mm in length and has a characteristic bright metallic green colouration. The common name derives from the tansy plant on which they often feed as both larvae and adults. In addition to the nominotypical subspecies, which repeats the specific name, C. graminis graminis, there are five further distinct subspecies of tansy beetle, which, collectively, have a Palearctic distribution, although in the majority of countries where it is found the species is declining. In the United Kingdom it is designated as 'Nationally Rare' and this localised population, centred on York, North Yorkshire, has been the subject of much recent research.