Cercyon impressus (Sturm, 1807)

This western Palaearctic species occurs across Western, Central and Northern Europe from the Portugal to Italy, Hungary and Ukraine in the south and north to the UK, Denmark, the Baltic countries and Western Russia where it extends to the far north of Norway and Sweden. It is locally common in warmer southern regions but generally common and often abundant in cooler mountain regions, where it occurs up to 2400 m in the Alps and above 1700 m in the Carpathian Mountains, and in the north. It has also become established in parts of Pacific North America following introductions from Europe. In the UK it is generally common throughout England and Wales, including all the islands, and more local further north to Orkney and the Western Isles, it is widespread in Ireland, seemingly common in the north but much more local and scarce in the south. The species is associated with decaying organic matter in almost any situation; it is often common in cattle and sheep dung on pasture or in that of horses, deer and fox etc. in woodland and parkland, it may be common in compost, decaying fungi or among litter in most situations, including wetlands and coastal dunes etc., and it often occurs in disturbed areas such as wasteland and domestic gardens. Adults are present year-round, they may remain active in garden compost or decaying fungi etc. through the winter but they generally overwinter among litter or in moss or tussocks etc and are active over a long season from March until November, peaking in abundance during May or June. Adults are saprophagous while the predatory larvae develop rapidly among host material during spring and summer. Adults may be found by sieving organic matter or in extraction samples at any time but they fly readily on warm days and often occur in flight-interception and dung or fermenting fruit-baited traps in numbers.