Leistus terminatus (Panzer, 1793)
This widespread species occurs across most of Europe from France to Asia Minor although it is generally absent from the Balkan countries and some southern Mediterranean areas, it extends north to the UK and above the Arctic Circle in Scandinavia and east through Siberia to the Pacific coast of Russia, in many central and northern areas of Europe it is locally common but in the south it is more sporadic and generally scarce eg it is extremely rare in Switzerland and certain parts of southern Germany. Here it is very local though widespread with records to the far north of Scotland including the Western Isles, Orkney and Shetland and across the north of Ireland; it is often quoted as common but in our experience there has been a sharp decline over recent decades. It is the most hygrophilic of our British species, preferring moist or even wet conditions; typical habitat being permanently damp and shaded woodland with plenty of leaf litter, wooded areas in fen districts, carr and moist grassland and moorland or even under debris beside streams and peat bogs. Adults occur year-round, peaking in abundance during April and May and again in the autumn, they breed from July and gravid females have been observed into November. Larvae develop through the winter and into the spring, they pupate in the soil during April and May and this stage lasts about ten days, the development from egg to adult taking about eight months. New generation adults eclose during May and June and spend a few weeks feeding before aestivating during the warmest part of the summer, they emerge in late summer and resume feeding for a while before breeding. Many of these will overwinter in the soil or among litter etc and become active early in the year, February or March, but most die off after mating and ovipositing and it is thought that this generation will mostly perish before the next appears. Adults are wing-dimorphic throughout the European range, including the UK, but it is not known whether they disperse by flight, they are very active and mostly nocturnal surface predators and, as with all members of the genus, along with the larvae are specialist collembola predators. They are readily sampled by general searching in likely habitats but adults often occur in numbers and so pitfall traps can be very destructive and should be used with caution.
6-8mm. readily identified by the shiny reddish-brown body and black head, among our UK members of the genus the only confusion might be with ferrugineus but the present species has a distinctive pronotum which is broadest in front of the middle and evenly narrowed to obtuse hind angles, compared with ferrugineus the elytra are also darker, generally with the apex and/or suture darkened, the abdomen is entirely dark brown to black and the elytral striae are generally less developed with sparser and weaker punctures, and are more obliterated towards the apex. This is among the most easily recognized of our carabid genera, the widely transverse and cordate pronotum, elongate-oval elytra and long appendages are distinctive and should not be confused with any other genus.