11 January 2010
This beautiful, large (c.10 mm), iridescent green species is now found only along a 30 km stretch of the banks of the River Ouse around York. The beetle is endangered not only here but across its worldwide range. Its food plant, Tansy, is widespread, but factors such as shading by willows and Himalayan Balsam and livestock grazing have led to Tansy clumps disappearing, creating isolated beetle populations that can no longer reach one another.
Latin name:Chrysolina graminis
Population numbers: We know nothing about population sizes in the past. On the River Ouse, reliable evidence puts the beetle around 9 km further north than its current northern limit (excluding reintroduced populations). The species was definitely at Wicken Fen in Cambridgeshire, but was last recorded there in 1981.
Where to see and when: Adult beetles are active on Tansy clumps in either April/May or August/September, and most obvious on warm, sunny days. Look for these from public footpaths along the Ouse running either side of York.
What’s being done: The Tansy Beetle Action Group, made up of North Yorkshire County Council, the City of York Council, the Environment Agency, and the University of York, has secured funding from the SITA Trust over three years to undertake a number of conservation measures, including:
removing riverside willow and Himalayan balsam, which reduce Tansy growth
planting Tansy clumps in large gaps to increase beetle movement, as they can only walk a maximum of 200 metres
creating safe havens away from the river where beetle populations can be protected from summer floods, which cause high mortality
reducing grazing pressure on Tansy by using short-term fencing and livestock management
ensuring that during Ragwort eradication work, riverside land owners know the difference between Tansy and Ragwort.
Action for Tansy beetles Environment Agency