Blue mint beetle
The blue mint beetle, Chrysolina coerulans, was found breeding in Britain in 2011, it has now been found in southern and eastern England and in Edinburgh. The beetle is widespread in mainland Europe and it may spread further in Britain. It is often confused with alder leaf beetle and fuchsia flea beetle.
Blue mint beetle is a leaf beetle (family Chrysomelidae), there are about 250 species of leaf beetle found in Britain. Almost all feed on living plants, most are do not have a noticeable effect on garden plants. They range in size from size from 1 mm to 18 mm, many are colourful and many species are local or rare. More information on British leaf beetles can be found from UK Beetles.
Scientific name Chrysolina coerulans
Plants affected Mint (Mentha spp.)
Main symptoms Holes in foliage, beetles on leaves
Most active Spring to autumn
What does it look like?
- The adult beetle is 7mm long and is a metallic dark blue
- The larvae reach about 1cm in length, have soft rotund bodies that are blackish
- Both adults and larvae feed on the foliage of cultivated and wild mints, Mentha spp.
- It can easily be confused with alder leaf beetle and fuchsia flea beetle, blue mint beetle is only found on mint and is larger than the other two species
Are there other insects that eat mint leaves?
Are there other dark blue beetles?
Do I need to control blue mint beetle?
- Blue mint beetle and other insects that feed on mint can be encouraged as part of the biodiversity these plants support in a healthy garden, They are unlikely to be numerous enough to cause significant damage to healthy mint plants
- If necessary on small clumps of mint, it is feasible to remove the beetles and their larvae by hand
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.