With no systematic surveys to date, adding a new butterfly to the Harapan Rainforest list is easy. But imagine my surprise when, after sending photographs for identification to a colleague at the RSPB (Martin Davies - who is compiling a list from published sources of ‘potential’ butterflies at Harapan Rainforest ) one of them would seem to be a new species for Sumatra!I photographed several Tawny Costas Acraea violae here in August 2008 and again in early October 2009 but had no idea at the time what they were, as they’re not in any of the relevant books! Until fairly recently, the Tawny Costa was known only from the Indian subcontinent. However, it arrived in Thailand after 1980 and is now widespread throughout the country. By 1996, it had spread to the northern part of the Malay Peninsula and south to Selangor by 2002 where it is now common. There is also a documented record of this species in Sumatra from neighbouring Bengkulu Province in March 2009. At Harapan I’ve only seen them along the roadside and in the neighbouring oil palms so they are not a ‘true’ forest species but are an attractive addition nonetheless. What other surprises has Harapan Rainforest in store?