One of the most elusive and nationally scarce butterflies is quietly retaking London and the Thames corridor. The brown hairstreak is a beautiful, ginger-streaked insect that usually lurks unseen in the treetops in late summer.
It is easier to find the hairstreak’s minuscule white eggs than to find the butterfly – but only now, in midwinter, when the sea-urchin-like ova can be found on the bare branches of blackthorn, which thrives in hedges and copses on clay soils.
Thanks to sharp-eyed egg hunters such as Liz Goodyear of Hertfordshire and Middlesex Butterfly Conservation, it is being discovered in dozens of new locations around London. The butterfly is increasing south of the Thames from Putney to Wimbledon Park and its eggs have this winter been found in some unexpectedly urban locations farther north: across Wormwood Scrubs, beside Yeading Brook, in Margravine cemetery in Hammersmith, in Totteridge and eastwards to Rainham Marshes and Thurrock.
Throughout the 20th century, this butterfly was vanishing from Britain. Now it is colonising new areas. “It must be climate change,” says Goodyear. “It is doing very well generally.”
To thrive further, blackthorn hedges must be cut on a longer rotation – not every year – and then more eggs will survive. So now is the time to go egg-hunting and help put this expanding species on the map.
