The adult beetle is 7mm long and is a shiny dark blue colour.  The larvae have soft rotund bodies that are blackish in colour. Both adults and larvae feed on the foliage of cultivated and wild mints, Mentha spp.

The blue mint beetle, Chrysolina coerulans, was detected breeding in the UK for the first time in July 2011. The foliage on mint plants in a garden at Newenden, Kent was being eaten by the adults and larvae of this insect. In September 2012 the beetle was confirmed as breeding in several locations in the vicinity of Ely, Cambridgeshire. The beetle is of widespread occurrence on the mainland of Europe and it may now spread and become a problem in the UK. This specimen was captured in Porthkerry Park, Barry, Vale of Glamorgan, UK.