Notes on the dolichopodid flies of two contrasting Yorkshire bogs

摘要

Askham Bog near York (SE575481, VC64) is a 44.fha remnant of a post-glacial mire at an altitude of c.lOm which formed behind a terminal moraine to the south, along whose summit now runs the dual carriageway of the A64 York by-pass. It has long been known as a haunt of rare fenland plants and insects, to the extent that in the past it was called 'the Wicken Fen of the North'. There is an account of a visit by boys of York Quaker (now Bootham) School in 1834 in search of water beetles and plants (Fitter & Smith, 1979), and in 1946 the site became the first, and for almost ten years the only, nature reserve of the Yorkshire Naturalists' Trust (YNT), as the Yorkshire Wildlife Trust (YWT) was then known.