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Exciting news - Brown Hairstreak butterfly seen

Date posted: Monday 23rd September 2019

Exciting news - Brown Hairstreak butterfly seen

A very exciting piece of RPA wildlife news from last month – a sighting of a brown hairstreak feeding on garlic chives on 25 August, by Jon and Carol! To our knowledge this is the first time a brown hairstreak butterfly has been seen on the RPA site. Jon said, ‘It made a very short visit of about 30 seconds and we made a provisional identification. It then returned later and spent about an hour feeding on the garlic chives which allowed us to look in great detail and confirm our identification and take its photograph.’

Jon emailed Helen, our butterfly expert with query about the rarity of brown hairstreaks in the SE and she replied: ‘..there are known colonies, for example, out past Tolworth, towards Ewell and Epsom (indeed I have a friend who lives out that way who has seen them in his garden). However it’s certainly of interest that they may be moving further over this way – I’m not aware of other sightings so far in our more immediate vicinity. So great stuff – and well-spotted Jon! I’ve reported to Butterfly Conservation (who monitor butterfly distribution) with a grid reference – let’s see if they respond.’

A week later Helen emailed me to say: ‘Re brown hairstreaks, I just thought I’d add that (as you might expect) we’ve been keeping an expectant eye out ever since Jon’s sighting on Sunday, but sadly no return visit so far… (however I’m crossing my fingers that she (it was a female) might have taken a liking to the blackthorn in the hedge at the back of my plot for egg-laying, as that’s the brown hairstreak foodplant. Never know your luck…!)’. This is the photo Jon took:

This very significant wildlife news should have been put up on the Blog earlier, but the Autumn Social organising has been taking up most of my time recently, so apologies to Jon, Carol and Helen! We hope that other plotholders might keep a look out and report any further sightings of this unusual (in these parts) butterfly. Some information from the Wildlife Trusts website:

Brown Hairstreak Butterfly Thecla betulae, wingspan: 3.6-4.5cm. Protected in the UK under the Wildlife and Countryside Act, 1981. Priority Species under the UK Post-2010 Biodiversity Framework. Seen from July to September.
The largest of the UK’s hairstreaks, the brown hairstreak is an elusive butterfly that spends most of its time either high in the tops of large ash trees (called ‘master trees’), or among thick hedges. It is found at woodland edges and along hedgerows in southern England from late July until November. Adults feed on honeydew from aphids, while caterpillars feed exclusively on blackthorn.
The brown hairstreak is a large hairstreak, with brown upperwings and small ‘tails’ protruding from the hindwings. Females have a brilliant orange patch in the top corner of each forewing. The underwings are a distinctive bright orange, with two white lines streaked across them.
Distribution: found in scattered locations in southern England and Wales.
Female brown hairstreak lay conspicuous, round, white eggs on young blackthorn shoots. Looking like blackthorn leaves, the older larvae are extremely well camouflaged and feed only at night. (Wildlife Trusts)