Pterostichus oblongopunctatus (Fabricius, 1787)
This species is locally common from lowland to alpine mountain altitudes throughout Europe from northern Spain to Greece and north to the UK and northern provinces of Fennoscandia but not reaching the Arctic Circle, to the east it extends through Asia Minor and Russia to the far east of Asia and Japan. In northern Europe it has become more frequent over recent decades and it may be expanding its range but it remains very local in the UK; it occurs throughout the mainland and extends to the Hebrides and Shetland but the distribution is patchy e.g. it is scarce in the south-east of England, the West country and eastern Wales but locally common in western Wales and the east midlands, it is largely absent from Ireland and currently known only from populations along the north east coast. Typical habitats are established open and dry woodland with plenty of fallen timber and decaying stumps etc, it occurs mostly in broadleaf and mixed woodland although in northern Europe it is frequently common in extensive spruce forests, reaching to the top of the tree line in mountain areas; it is absent from the northern European dune forests and at higher altitudes often occurs on moorland and alpine grassland. Adults are present year-round; they overwinter among litter or under logs and in old stumps and are active over a very long season from early spring, peaking in abundance during May and June and again in the autumn, they are mostly nocturnal and even then they tend to remain hidden among litter and moss or under logs etc. Reproduction occurs during the spring but mostly in May and June, they are active for only a short while afterwards before entering a summer diapause which may last until late in the summer, and many of these adults will reproduce a second time during the following spring. Females lay small groups of eggs in the soil or among litter and each will produce between 50 and 130 eggs in a season, larvae develop through the spring and summer and pupation occurs late in the year. So far as is known all larvae will pupate late in the year; development is influenced by temperature, especially in the third stage, but none will go on to overwinter, even at higher altitudes and latitudes. Both adults and larvae are predatory although both stages also consume at least some decaying plant material, they hunt springtails and early
stages of small insects etc. among litter and under debris, and larvae are known to be cannibalistic at high densities in northern European forests, in central Europe they are common but tend to occur in lower densities due to competition from a more diverse woodland carabid fauna. Wing development varies widely; many specimens have reduced wings and weakly-developed flight muscles and while flight has not been observed directly, it has been inferred from specimens found at long distances from the usual habitats, the species may disperse by walking but they do not roam over the long distances seen in e.g. Carabus, and an effective dispersal of 2 m per day, or 20 m each season, has been estimated from field observations. Sampling adults is easiest by pitfall trapping as they tend to lead secluded lives but they will sometimes occur under loose bark or among wood debris and under logs.
9.0-12.5 mm. Body shiny black or with a faint brassy or, rarely, bluish or green metallic lustre, legs dark brown with black femora, palps brown, antennae black; females may have slightly duller elytra. Head with prominent convex eyes and strongly converging temples, surface very finely punctured and wrinkled, with two setiferous punctures beside each eye, antennae densely pubescent from the fourth segment, the basal segment as long as the third segment. Pronotum transverse, widest in front of the middle and sinuate before perpendicular posterior angles, the lateral margin very narrow throughout, basal margin almost straight, surface with a long basal fovea either side, any punctures generally confined to the fovea. Elytra with rounded shoulders, slightly broadened behind the middle and very weakly constricted before the apex, with a complete basal border and striae well-impressed to just before the apex; the sutural stria with three small punctures towards the apex, scutellary striole well developed, interstices slightly convex, the third with four (or more) setiferous fovea joining the second or third striae, epipleura crossed before the apex. Legs long and robust, all tibiae with long apical spurs, and the front tibiae expanded beyond the antennal-cleaning notch. Tarsi smooth and glabrous, the apical segments without ventral setae or dorsal furrows, and the basal segments of the front tibiae expanded in the male.