August field meeting at Nostell Priory

The Society’s final outdoor meeting of a full summer programme for this year attracted a very good attendance on 13 August 2017.  Members were greeted with a fine sunny morning and treated to some special wildlife sightings as we walked around part of the Nostell Priory parkland, which is managed by the National Trust.

comma butterfly caterpillar

purple hairstreak butterfly

The bottom lake provided good views of various dragonflies and damselflies, including brown hawker and common blue damselfly patrolling around a large area of fringed water-lily with its attractive yellow flowers.  Large bracket fungal fruiting bodies of Ganoderma spp on old oak trees and a giant polypore (Meripilus giganteus) at the base of a mature beech tree were also noted.  Eagled eyed members spotted a couple of caterpillars of the comma butterfly feeding on nettles at a woodland edge.  The white markings on their backs are thought to resemble a bird dropping, perhaps a good defence mechanism. See attached image.  Possibly, the highlight of the morning was the appearance of a purple hairstreak butterfly high in the canopy of an oak tree, which is the food plant of its caterpillars.  Although the adult butterfly may sometimes be seen at lower levels it spends much of its time searching high in the tops of oak trees and occasionally other species for honeydew from aphids.  For this reason it is easily overlooked and under recorded and certainly it was difficult to photograph on the day.  Other butterflies seen, included red admiral, speckled wood and meadow brown. Other interesting wildlife included a hornet’s nest in an old veteran tree and knopper gall on oak.

The knopper gall is caused by a small wasp (Andricus quercuscalicis) laying its eggs in the young acorns of pedunculate oak.  This tiny insect forms a second generation in the spring when it lays its eggs and forms small galls on the male catkins of turkey oak (Quercus cerris), which can be found in small numbers at Nostell Priory.  At this time of year the acorns become increasingly wrinkled as they develop.  In some years this can reduce the number of viable acorns produced.  However, many may remain unaffected and perhaps this insect may not be the threat to our native oak that it once feared to have been.

4.meripulus giganteus

Encouraged by the visit I returned to Nostell on the 17 August to photograph the giant polypore, which was by then much larger.  I also noted a further three purple hairstreak butterflies in the same area, together with a brown hawker and migrant hawkers.  Images of the brown hawker, which rested for a matter of seconds on a fence post, together with the migrant are attached.

migrant hawker

brown hawker

The indoor meetings resume on Tuesday September 12^th at 7.30 p.m. at the Quaker Meeting House, Thornhill Street, Wakefield WF1 1NQ with a presentation by Steve Rutherford when he will take us on a journey around the islands of the UK.