Butterfly buffs received an August boost with brown hairstreaks emerging from seclusion to provide decent views and pose for photographs. Brown hairstreaks are red-listed species of high conservation concern in the UK and extremely difficult to survey accurately. This is mainly because they lurk around the tops of “master trees” like ash so fleeting and distant views are often obtained only with back-breaking, eye-straining patience. Males rarely venture down towards ground level and the best chance of seeing brown hairstreak is to spot females descending for egg-laying missions on blackthorn – but not before 11am on sunny days in August and September.
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My first sightings of this elusive butterfly came on Bookham Common, Surrey, on August 14, 2021. Disappointment at brief, distant views of a treetop male soon dissipated as two females with wings closed perched nearby on eye-level blackthorn, clearly displaying their underwing streaks.
Sussex seems a recent hotspot with sightings at Eastbourne, Weir Wood Reservoir and Seaford. One lucky correspondent to the Butterfly Conservation website reported seeing brown hairstreaks in his West Worthing garden every year since 2021 and another claimed sightings of 45 in three visits to Steyning rifle range. They can be found in Bexley too. Two were seen on Crayford marshes during August, others photographed at Hall Place and brown hairstreak became the 26th butterfly species recorded on Abbey Wood’s Crossness Nature Reserve when manager Karen Sutton spotted this site first. She said: “It would be exciting to think it will be a breeding species at Crossness where we have blackthorn for breeding and bramble for food.”
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Crossness Nature Reserve is run by Thames Water with an eye for conservation. Ironically, workmen acting for Thames Water unintentionally scuppered hopes of brown hairstreak breeding at Chislehurst Common. A single brown hairstreak egg had been found there in a hedge bordering the cricket ground in 2023. No brown hairstreak butterflies were seen then or in 2024 but this year Thames Water workmen unknowingly destroyed part of the hedge where the brown hairstreak egg had been discovered. No brown hairstreaks were seen but it is hoped they may visit when the hedge re-grows. Brown hairstreaks have been spotted nearby near National Trust land at Petts Wood.
Despite the absence of brown hairstreaks, Chislehurst Common seems a magnet for butterflies with 19 species recorded there this year.
