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Chrysolina graminis

Tansy beetle - Geoff Oxford 2.JPG

A spectacular, large, green leaf beetle, with a distinctive coppery sheen. The Tansy beetle is one the UK's most stunning insects.

  • Rarity: The Endangered Tansy beetle is restricted to a 45km stretch of riverbank centred on York, as well as two small areas in the Cambridgeshire/Norfolk Fens

  • Causes of decline: The Tansy beetle is dependent on Tansy plants along the River Ouse and other foodplants in the Fens, which are becoming more scattered due to changes of land use and competition with invasive plants; and beetle declines are also caused by summer flooding

The Tansy beetle is an iridescent green leaf beetle that is affectionately known as the 'Jewel of York'. This beautiful beetle is roughly 1cm long - about a quarter of the size of a one pence coin.


The Tansy beetle was once more widespread in Britain, but this striking beetle is now restricted to the banks of the River Ouse (near York) and small areas of the Cambridgeshire Fens. The declines in the Tansy beetle's population and restricted location means it is a conservation priority and is listed as Endangered (at risk of extinction) on the national Red List of threatened species.

The banks of the River Ouse near York are a nationally important area for the Tansy beetle, as it is where a large proportion of the British population is found. Therefore, it is important that the banks are managed for the Tansy beetle and its foodplants. 

In the Fens the Tansy beetle lives on wetland sites along the edges of ditches. Feeding on plants such as Water Mint, Gypsywort and Marsh Woundwort. There still needs to be research to understand the beetle and its conservation in the Fens.

​Threats to the Tansy beetle on the Ouse, include:

  • Tansy plants uprooted when mistaken for Ragwort 

  • Tansy plants eaten by high numbers of grazing animals

  • Tansy clumps outcompeted by willow or invasive plants such as  Himalayan balsam

  • Mowing the riverbank when the beetle is vulnerable (March to October)

  • Bank erosion and summer flooding

 The Tansy beetle is particularly vulnerable during the reproductive phase of its life cycle i.e. between March and September. Cutting, heavy grazing and other operations that remove Tansy plants should be avoid during this time.

Tansy beetle showing relative size - Geoff Oxford.JPG


  • The Tansy beetle is monitored annually in York and the Fens. The SRT supports the volunteers gathering the data.

  • Monitoring results have shown an annual fluctuations in numbers, relating to environmental conditions and specifically declines due to  summer flooding.

  • Despite fluctuations the overall trend in beetle numbers is upwards over the last ten years, as habitat management along the River Ouse improves.

  • The SRT writes management plans for land managers to improve habitat management for the beetle. This includes organisations such as the Environment Agency, National Trust, Carstairs Trust, York City Council and St Nicks.

  • The SRT also leads the Conservation Plan for the beetle, this is currently being redrafted, with a new 5 year plan which was published in 2023

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