Field meeting, 14 August 2016: The Ashfields, between Heath village and the River Calder (OS ref. SE 353 206), were settlement lagoons for the pulverised fuel ash from Wakefield power station which was decommissioned in 1991. In the past thirty or forty years the process of natural succession has transformed them from silty open ground to orchid meadow and then from scrub to woodland.
Two longhorn beetles, Stranglia maculata, rest on umbels of hogweed and in a sheltered clearings and there are a few speckled wood butterflies but the most common and persistent insect is the mosquito.
The Half Moon (SE 358 208) between Heath and Kirkthorpe is a cut-off meander of the Calder. A hundred or more whirligig beetles gyrate in a group on the surface close to the bank. Branched bur-reed grows amongst sweet-flag.
Amber snails graze on the sweet-flag. These snails are unable to fully retract into their shells. Their lower tentacles are much reduced.