The Marbled White, Melanargia galathea.
This species is not local to the Yeldham area. They can be found in the south of the county with a good population on Canvey Island.
In Cambridgeshire I have seen a few on Magog Down near Cambridge, on the Devil's Dyke and at Woodwalton Marsh.
The Marbled White has only one brood per year. The larval food plants are various fine-leaved grasses, and it over-winters as larvae.
The adults are on the wing from late June to early August.
In overcast conditions the butterflies perch for long periods in full view on grasses or other plants with the wings either closed or held flat open as
in the first three photographs above. As soon as the cloud passes they become active, stopping briefly on flower heads to take nectar.
16 June 2011. Woodwalton Marsh. 6 Marbled Whites.
3 July 2011. Devils Dyke. Newmarket Heath. 1 Marbled White.
15 July 2011. Magog Down. 3 Marbled Whites.
9 July 2012. West Canvey Marsh. On a dull day c. 20 by the car park, 13 others mostly near the sea wall.
15 July 2012. Magog Down. 14 Marbled Whites, mostly in the sheltered north-east corner.
17 July 2012. Magog Down. 9 Marbled Whites.
22 July 2012. Sugley Wood, Gamlingay. 30 + Marbled Whites.
22 July 2012. Therfield Heath, Royston. 23 Marbled Whites, mostly in the longer grass on the higher ground.
16 August 2012. West Canvey Marsh. Mostly overcast, late morning, 3 Marbled Whites, getting a bit faded.
11 July 2013. Twywell Hills and Dales. Hot. Marbled Whites, 4 in Picnic Meadow, 6 in Whitestones.
27 June 2016. Twywell Hills and Dales. Coolish, clouding over. Marbled Whites, 3 in Picnic Meadow, 8 in Whitestones.
26 July 2016. Fleam Dyke, Balsham. 1 Marbled White, very active on a hot day, the first which I have seen here.