The LNHS Horsenden Hill meeting, which was the first time I'd seen White-letter Hairstreaks, was a useful event for getting my 'eye in' and was absolutely instrumental in enabling me to find the species along Moat Lane on Crayford Marshes today. I was also spurred on by Tristan Bantock having said he also thought there was a good chance of it being there when we were making our way along the lane towards Slade Green aftera bug-hunt earlier in June.
Moat Lane, Crayford Marshes, on a sunny evening back on the 23rd April 2010. The substantial English Elm 'hedge' where the White-letter Hairstreaks were found is on the left (south) side, here catching the evening sun from the west.
The lane has longish stretches of English Elm 'monoculture' to about 18-20' tall along the south side, and a few rather smaller ones on the north side. Horses are pastured on the rough grazing adjacent to the hedge. I saw between 7 and 9 likely different individuals, two of which I got side-on good binocular views of and so can be absolutely certain of the ID. They appeared to only be using the (south side) Elm some way along the lane at present (around TQ 530 767), and not that near the Slade Green station end or opposite the moat of Howbury Grange.
The weather was hot and sunny, with some blustery breezes and the odd dark cloud blotting out the sun for short periods. The observations were made between 11.40 a.m. to around 13.30.
The White-letter Hairstreak is a UK and London Borough of Bexley Council BAP priority species, and the Council's website says the only place it occurs in the Borough is in a wood at Foot's Cray Meadows.
Other species seen along the lane today were:
Probable Holly Blue
and a couple of female Broad-bodied Chasers and Darter species.
There were 4 Swallows (probably fledglings) sitting on the barbed wire fence of the field around the moat, and a few Swifts overhead.
Coming hard on the heels of the W-LHS find, a little further along the lane towards the River Darent were 2 or 3 clumps of Crown Vetch, my second find of it in the Borough - the other also having been on the Marshes, in that case away to the west near Crossness.
Out by the river were a Small Heath, 2 Common Blues, a Kestrel and Tufted Vetch.