Leistus ferrugineus (Linnaeus, 1758)
This species is generally common throughout Europe except for some eastern Mediterranean areas, extending north to the UK and the far north of Scandinavia and east through Ukraine and western Russia; it has also recently become established in western Canada through introductions from Europe. In the U.K. it is locally common throughout England and Wales, although less so in the west, and very local and scarce through Scotland including the Western Isles but not Orkney or Shetland. From our own experience there has been a general decline in abundance since the 1970s and it is now absent from or very infrequent in many of its local haunts. The species occurs in a wide range of habitats, in Europe more generally in humid woodland, meadows and peat bogs etc, but in the UK tending to prefer more open and dry situations; among tussocks and litter or under debris on grassland, moorland and dunes but also under logs on wooded margins, hedgerows and parkland. Adults sometimes climb vegetation and so may occasionally be swept but in general they hide during the day in the soil or among litter etc. and become active nocturnally when they may frequently be seen in the open running on pathways etc, they sometimes overwinter in numbers under logs etc but otherwise they are mostly solitary and so, unlike other members of the genus, are rarely found in numbers. Both adults and larvae overwinter, adults become active early in the year, from February or early March, but it is thought these die off before the next generation of adults appear, they are flightless and so disperse by walking but nonetheless they can be quick to colonize new situations in the spring. New-generation adults eclose during late spring and early summer and spend a while feeding before aestivating period during the warmest part of the summer, they become active from late August and resume feeding for a while before mating and oviposition occurs through September and October. Larvae develop through the winter, hunting and feeding in all but the coldest conditions, and pupate in the soil in the spring. As with all members of the genus both adults and larvae are specialist springtail feeders.
This species is distinguished among the U.K. fauna by the entirely orange or red colouration, teneral specimens are very pale but gradually darken with age, teneral specimens of other members of the genus may be confused with ferrugineus but they are soft-bodied and soon develop their dark colour. Mature specimens might be confused with terminatus but here the head and abdomen are contrastingly dark and the pronotal hind angles obtuse, and the present species is generally narrower, paler in colour and less convex. 6.5-8.0mm Elongate, flattened and with long and slender antennae and legs, entirely pale to dark brown, usually with the appendages and mouthparts lighter. Head convex, smooth not, or only vaguely, wrinkled laterally, with large convex and prominent eyes and widely dilated mandibles, all segments of the maxillary palpi long and slender. Pronotum cordate and widely transverse, broadest in front of the middle and strongly narrowed to a short and near parallel margin before perpendicular hind angles, explanate margin narrow, sparsely punctured and lacking a seta at the base, surface smoothly convex, with a variously-developed median longitudinal impression and punctured across the base and apex. Elytra narrow and only weakly rounded to a continuous apical margin, without a shoulder tooth, striae deeply impressed and strongly punctured to about the middle then weaker and generally obliterated some distance before the apex.