Pill beetles have rounded, convex bodies (3). The mire pill beetle, or 'bog hog' is tiny, measuring just 2 mm in length, and is black in colour (1). It was first found in Great Britain as recently as 1977 (4).
Very little is known of the ecology of this species. Both adults and larvae of the mire pill beetle feed on moss, and can be found just below the surface of the soil, typically amongst Sphagnum moss or heather litter. Adults have been recorded in April, May and July, and have been found living in moss-lined tubes (4).
Three sites are known to support the species, all of which are in the Humberhead Levels of south Yorkshire and Lincolnshire (2). Thorne and Hatfield Moors are the largest sites, and each support many small and fragmented populations (2). A small isolated population was found in a tiny patch of suitable habitat at Haxey Grange Fen (2). Outside of Britain, this pill beetle occurs in southern Sweden, Denmark and northern areas of Poland and Germany (5).
As the common name suggests, this species inhabits lowland raised mires (2), which take the form of raised mounds of peat, the surfaces of which are above the water table (6). This beetle seems to prefer damp, open peat where plenty of mosses grow (2).
This beetle faces a number of threats, including drainage of the mire habitat in order to allow peat extraction, fire, drought, shading resulting from scrub growth, and a decrease in the level of ground water, caused by water abstraction and general land drainage (2). Since 1970, the area of available habitat has been reduced by 80% on Hatfield Moor and 30% on Thorne Moors, largely as a result of peat extraction for use in horticulture (2).
The diminutive mire pill beetle is a UK Biodiversity Action Plan (UK BAP) priority species (2), and is included in English Nature's Species Recovery Programme (6). The Species Action Plan produced under the UK BAP aims to maintain all current known populations, and to enhance these populations before 2010 (2). All three sites are designated Sites of Special Scientific Interest (SSSI), and large areas of Thorne and Hatfield Moors are owned by English Nature. These sites therefore receive a level of protection (2).
The UK Biodiversity Action Plan for this species is available at UK BAP.
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