Ground beetles belonging to the genus Dromius are typically elongate, flattened beetles (2). Dromius sigma has a black head (2), and pale brown wing cases (elytra) that have a dark 'maltese cross' pattern (1).
The adults are believed to be wingless in Britain (4). The life cycle of this beetle takes one year to complete; breeding is thought to occur in summer, and immature adults overwinter in clumps of tufted hair-grass (Deschampsia cespitosa) (4). Both the adults and the larvae prey upon small invertebrates (4).
Inhabits muddy and peaty soils close to standing water in fens, marshes, and flooded gravel pits or quarries (4). It is found on soft mud or soil close to the water margin, typically in lush vegetation such as clumps of tall grass (5).
Main threats are the drainage of wetlands for agriculture or development (5), as well as peat extraction for use in horticulture (4). Further threats are the infilling of gravel pits, tree growth on moorland, and lowered water tables due to water abstraction and river engineering works (5).
This ground beetle is included in English Nature's Species Recovery Programme, and is a priority species under the UK Biodiversity Action Plan (UK BAP). The Species Action Plan that has been produced to guide the conservation of this beetle aims to maintain its current range (4). A number of sites currently supporting this species are either Sites of Special Scientific Interest (SSSIs) or National Nature Reserves (NNRs); they are therefore afforded a level of protection (4). It has been suggested that management for this species should aim to maintain high water tables, and protect water bodies from pollution (5).
The UK Biodiversity Action Plan for this species is available at UK BAP.
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