Lepidoptera Rostherne Mere
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MANCHESTER ENTOMOLOGICAL SOCIETY THE LEPIDOPTERA OF ROSTHERNE MERE NATIONAL NATURE RESERVE by H. N. MICHAELIS P R IC E 10/6 Date o f Publication—1965 Published by the Society and obtainable from the Hon. Secretary, E. H. Fielding, 83, Hale Road. Hale, Cheshire. MANCHESTER ENTOMOLOGICAL SOCIETY (FOUNDED 1902) PROCEEDINGS AND TRANSACTIONS 1964-1965 incorporating the 62nd and 63rd ANNUAL REPORTS THE LEPIDOPTERA OF ROSTHERNE MERE NATIONAL NATURE RESERVE by H. N. MICHAELIS With an Introduction by P. H. Oswald, Nature Conservancy. MANCHESTER ENTOMOLOGICAL SOCIETY 3 INTRODUCTION By P. H. O sw ald THE MERES AND MOSSES The lakes and bogs of the North-West Midlands, locally called meres and mosses, lie in glacial hollows scattered in a plain between the Potteries and the Welsh Mountains and extend from Manchester to Shrewsbury, In ancient times there must have been great expanses of marsh and bog in the lower parts, while the higher ground was probably covered with oak forest, but now nearly all the land has been drained and cultivated and only relics of the original forest remain. Almost the only remnants of the natural landscape are the meres and some of the mosses; the latter were originally open meres which were subsequently covered over, but not always completely filled, by sphagnum moss and other vegetation. ROSTHERNE MERE Rostherne Mere is the largest and deepest of the northern group of Cheshire Meres lying between Northwich and Altrincham, comprising Tatton, Mere, Rostherne, Tabley, Pick and Budworth (or Marbury) Meres and several smaller waters. The Mere is pear-shaped, narrowing towards the north with its long axis running N.W. to S.E. It is situated in typical undulating Cheshire countryside, surrounded by glacial moraines carrying a patchwork of pasture, arable fields, and woodland, and, like most of the meres in the North-West Midland Plain, it is not easily visible from any distance, as it lies in a hollow. The village of Rostherne cannot be seen from the Mere, and one gains the impression when on its banks that it is situated in a remote and thinly populated area, only a few scattered farms and cottages and Rostherne Church being visible, though in fact it is under three miles from Altricham and only ten from the centre of Manchester. The Mere is nearly three-quarters of a mile (1,285 yards) long, from the northern tip to the outlet at the S.E., and nearly two-fifths of a mile (695 yards) across its great est width at right angles to this line, from near the inlet at the S.W. to Mere Covert on the N.E. bank. O f its circum ference of about 3,330 yards, approximately 2,000 yards, or nearly two-thirds, are bounded by woods or osier beds; a further 400 yards have been planted with a line of osiers, and scattered alders grow along about 300 yards of the south MANCHESTER ENTOMOLOGICAL SOCIETY bank. Reed beds extend round more than half of the margin and there are smaller patches of other aquatic plants The water of the Mere is about 70 feet above sea level. The 100-foot contour often approaches within a hundred yards of the water’s edge and is never more than 220 yards from it except where streams run in and at the outlet. The steep descent is most noticeable along the south bank, where the Church overlooks the Mere, and the best and most com plete view of the water is obtained from a point on the ridge about a hundred yards east of the Church, where the A.W. Boyd Memorial Observatory has been built. THE NATIONAL NATURE RESERVE As early as 1915 the importance of conserving Rostherne Mere was recognised by the Society for the Promotion of Nature Reserves, who placed it on their priority list. It was recommended that it should become a National Nature Reserve by the W ild Life Conservation Special Committee in their report, ‘ Conservation of Nature in England and Wales ’, published in 1947, as being ‘ the most important of the Cheshire Meres, valuable both for its phytoplankton and its wildfowl . outstanding both as a winter resort of wildfowl and as a breeding place for certain aquatic birds ’ and because ‘ the insects are also of interest ’. The Mere and nearby woods were gifted to the Nature Conservancy by the Executors of the late Lord Egerton of Tatton and declared a National Nature Reserve, together with some of the surrounding fields in 1961. The Nature Conservancy have always recognised that the Reserve, besides being a \'itally important inland refuge for wildfowl, is invaluable for ecological research. It is notable in having ornithological entomological and hydrobiological records dating back over half a century which serve as a firm foundation for such research, and it is the Conservancy’s policy to promote scientific investigations and surveys such as that of the Manchester Entomological Society which can be integrated into the management of the Reserve and made compatible with the maintenance of refuge conditions for wildfowl and other birds. A BRIEF ACCOUNT OF THE VEGETATION The vegetation of the Reserve, which is fairly typical of the northern part of the Cheshire Plain, can be conveniently classified into permanent pasture, fields under rotation, woodland, osier beds, peat bog, marsh and drainage chan nels, and reed beds and other aquatic vegetation. MANCHESTER ENTOMOLOGICAL SOCIETY 'Fhere is nothing remarkable about the flora of the first two types, but patches of rushes (Juncus) and Marsh Thistle ( Cirsiiim palusire) in the wetter areas and scattered trees add to the variety of the pastures, and elements of a woodland ground flora are noticeable especially below the Church. The hedges are chiefly of Hawthorn (Crataegus monogijna). while Blackthorn fPrunus spinosa) is absent. Mucli of the woodland has been planted since the beginning of the nineteenth century on sites which are known to have been previously meadow or i)aslure and the whole of it has for many years been managed jirimarily for pheasant rearing and shooting. Rhododendron is extremely common and Sycamore (Acer pseudoplalanus) has been allowed to invade many overthinned and derelict .sections. It is probably fair to say that the woods are, basic ally, Oak (Qnercus robiir) woods, but more than twenty other species of trees occur there, some of them in small numbers. Alders (Alnus) are characteristic of the edge of the Mere, but there are also some large trees of White W illow (Salix alba) and Crack W illow (S.fragilis), the former chiefly in the N.W. corner of Merc Covert, and three species of poplars, two of them exotic but the native Grey Poplar (Populiis canescens) forming a clump, i>robably originally ])lanted, in Old Hall Wood. Elms (Ulnws) are frequent in Harj)ers Bank, and Ash (Fraxinus), Birch fBetiila) and Sweet Chestnut (Casiane.a) trees are scattered through the three largest woods, where there are also some well-grown specimens of Scots Pine (Pinas sylueslris) and Norway Spruce (Picea abies): Beech (Fagus). however, occurs only in the fields and in Old Hall Wood. By far the commonest comi)onent of the otherwise })oorly developed shrub layer is Rhododendron ponlicum, but Elder (Sambucus nigra) is locally abundant and brambles (Rubns) are dominant in many areas; Hazel (Corylus) is remarkably scarce. The herb layer of the woods is more varied. Fern.s or grasses are dominant over many areas, but in others there is a wide range of woodland ground flora. Sedges Onainly Carex acutiformis) are usually dominant along the wooded margins of the Mere, with patches of Yellow Flag flris pseudacorus) and Yellow Loosestrife ( Lysimachia imlgaris); Purple Smallreed ( Calamagroslis canescens) and Reed-grass (Phalaris arundinacea) succeed these and are in turn succeeded by low brambles (Rubus) further inland. Bittersweet (Solanuin dulcamara), Skullcaj) (Scutellaria galericulata) and, in Harpers Bank, Hemlock MANCHESTER ENTOMOLOGICAL, SOCIETY Water Dropwort (Oenanthc. crocala) are also typical of the wooded margins. Hosebay Willow-herb (Chamaenerioii angusfifolium) and Foxglove (Digitalis purpurea) grow chiefly on the drier margins and in the more open parts of the woods. The osier beds of Shaw Green and the Gale Bog have been planted with a variety of shrubby willows including Common Osier (Salix viminalis), Common Sallow (S.cinerea ssp. atrocinerea) and Bay W illow (S.pentandra), and in the former there are also Cricket-bat Willow-trees. In the herb layer, Lesser Pond-sedge (Carex acutiformisj, Reed-grass (Phalaris arundinacea), or Meadowsweet (Filipendiila ulmaria) is usually dominant according to conditions Such plants as Codlins-and-Cream (Epilobium hirsutumj, Purple Loosestrife (Lgthrum salicaria), Wild Angelica (Angelica syluestris) and Hemp Agrimony (Eupatoriuni cannabinum) are also conspicuous. The peat bog which forms the core of Gale or Gailey Bog has clearly degenerated seriously since the last century, when it supported not only Sweet Gale (Myrica gale), from which the bog took its name, but also Cranberry (Vacciniuni oxycoccos) and Marsh Fern (Thelypteris paliistris); these bog species are now extinct, as is the handsome Royal Fern (Osmunda regalis), though this has been seen in this century. Aspen (Populus tremula), Alder Buckthorn (Frangula alnus) and Purple Moor-grass (Molinia caerulea) still grow here but nowhere else on the Reserve, and there is a fair quantity of Marsh Cinquefoil (Poteniilla palustris). The most interesting marshy areas are in Brook Meadow, in Long Pasture north of the outlet, and along the south and south west margins of the Mere, and here there is a wide variety of plant species including two species of Cardamine, two of Rorippa, including Watercress, two Bur- marigolds (Bidens) and several Polygonum and Juncus species. Besides the reed beds (Phragmites communis), stands of other aquatic plants are scattered along the margin of the Mere.