Tansy beetle

This beautiful creature is one of the UK's rarest beetles. In recent times the tansy beetle Chrysolina graminis has been confined to wet grasslands alongside the River Derwent in Yorkshire, where it feeds on large clumps of tansy. It's a Biodiversity Action Plan species and lots of positive management has been undertaken to ensure the population survives.

Historically it was widespread in Great Britain, and was well known from the fenlands of East Anglia, where it fed on water mint rather than tansy. But it had not been seen there for many years and was thought to be extinct everywhere except the Derwent valley. That is until last week, when a certain entomologist found a population in a local area of undrained fen, feeding on water mint.This is very exciting and may stimulate more intensive survey to see whether it's still lurking in any other local wetlands. And it's so nice to have a rare beetle that's pretty - so often they're small and black!