The Straw Belle moth is now restricted to the North Downs and is found at just one site in Surrey, on National Trust land at Box Hill. It also occurs on a few sites in Kent. Even at Box Hill it is restricted to a small area, where it needs a varied chalk sward providing a range of conditions from bare ground and the short turf ‘hotspots’ needed by larvae, through to grass tussocks and scattered scrub that provide shelter for the adults.
In recent years volunteers from Butterfly Conservation have worked alongside NT to undertake management at Box Hill to secure and enhance the moth’s population. Cattle grazing was introduced at Box Hill in autumn 2013 using Belted Galloways from the Surrey Wildlife Trust herd, and a close eye has been kept on the effects of this on the vulnerable moth population. Cattle were excluded from part of the slope until we were confident that they would not overgraze it. Adult numbers of Straw Belle have remained stable under the new grazing regime.
Grazing pressure has varied over the slope, and last year it was evident that the top edge was becoming too dense and tussocky in places, so some small patches of the densest grass, a few metres in diameter, were strimmed and raked off to enable smaller plants, including Bird’s-foot Trefoil and Fairy Flax, thought to be among the Straw Belle’s larval foodplants, to grow and flower.
This has been successful, and in February this year, on the day when Storm Doris made being out on Box Hill a bracing experience, the new Surrey and SW London Branch conservation volunteer group helped NT assistant ranger Francisco to create further patches.
(from an article by Gail Jeffcoate)