Carabus nemoralis Müller, O.F., 1764
This is a locally common and often abundant species throughout central and northern Europe, extending north to 64 degrees and east as far as Moscow, and in many northern areas it is among the most common member of the genus; it is locally common throughout mainland UK though less so in western areas and, as in Europe generally, it has been increasing in abundance over the last century. Following introductions it is now widespread though generally synanthropic across the northern United States and southern Canada and, since 1990, has also become established at several sites in Iceland. It occurs in a wide range of habitats though in the UK it is less synanthropic than in Europe generally, it shows no particular preference for habitat or substrate type but is usually absent from peaty areas, otherwise it occurs on vegetated and often patchily shaded soils generally; on farmland, woodland, parkland and waste ground, under hedgerows and on grassland generally. Adults are nocturnal predators, usually roaming over large areas as they forage for other insects, larvae, worms and molluscs etc. and are easily observed on pathways and bare patches of soil by torchlight, and they are also occasionally active by day in the summer, they occur year-round but are generally active from April, or earlier in woodland environments, until the autumn, aestivating during the warmest summer periods. Mating usually occurs in the spring with oviposition soon afterwards, during April and May; the female digs small burrows a few cm. deep into which a single egg is laid and over a season she will lay between 30 and 50 eggs. Larvae appear from April; they are nocturnal predators and develop quickly, passing through 3 instars which take up to 3 weeks each to become fully-grown, and pupation occurs in the soil. The entire cycle from egg to adult takes about 3 months and new-generation adults occur from June or July depending upon the season. Adults mature in the summer and autumn and occasionally mate late in the year but spring is the main period of reproduction, they overwinter among moss and litter or deep within decaying stumps and logs, situations in which they also aestivate during the summer.
Adults are distinctive and unmistakable, 20-26mm and broadly rounded, greenish or purple bronze, usually with the pronotal and elytral margins contrasting red or green although a very rare entirely black form has been recorded in the UK. Head shiny black and roughly sculptured, with small but very prominent and convex eyes, robust mandibles and long antennae. Palps black with pale tips, penultimate labial palpomere with 2 setae (occasionally an extra one on one side) on the inner margin. Pronotum transverse (8:5) with explanate margins and posteriorly produced hind angles, surface sculpture weak on the disc and stronger towards the margins, black with the lateral and basal margins metallic bronze or purple. Elytra broadly rounded and convex, entirely metallic; green with bronze, red or purple explanate margins, each with numerous lines of irregular longitudinal granules, without more prominent ridges or carinae, and with 3 rows of small and shallow fovea which are golden-metallic at the centre. Legs long and robust, each tibia with 2 long apical spurs, pro-tibiae smooth internally i.e. without an antennal-cleaning notch. Basal pro-tarsal segments dilated in the male.