Carabus monilis Fabricius, 1792
This very local and generally scarce species has a restricted western Palaearctic distribution being confined to central and northern Europe from Spain and France to the Czech Republic and from Northern Italy to Germany and the UK, it is absent from Scandinavia although there is an isolated naturalized population in southeast Norway. In the UK it is widespread and was formerly common across southern England and the midlands, becoming more local and rare in Wales and further north to the Lake District, but there has been a drastic decrease in recent decades and it is now very local and generally rare, being lost from many of its former sites and now classified as endangered. There are a few old records from northern and western Ireland but it has not been recorded since the 19th century and is very probably extinct. Adults are flightless, disperse by flight and habitat fragmentation is thought to have contributed significantly to its decline. The species formerly occurred in a wide range of habitats including calcareous grassland, arable land, pasture, wetland margins and floodplains although it seems to have avoided permanently wet situations, and was also present artificial habitats such as parks, gardens and gravel pits. Both adults and larvae are nocturnal predators, hunting worms and other insects etc. on the ground, and open situations with little vegetation or short cropped grass may be important for this activity. Adults are long lived, on the continent they are known to live for 2 years and this seems likely in the UK as well, they are active from April until September and breed in the autumn.
This large and colourful species is distinctive due to the elytral sculpture which is suggestive of strings of beads and which gives rise to the common name. 22-26mm. Body entirely metallic green or coppery, appearing to have contrasting lateral margins to the pronotum and elytra from certain angles. Head quadrate and finely rugose, with large and very convex eyes and diverging temples, terminal segment of all palps only moderately broadened to the apex, penultimate segment of labial palps with 2 setae along the inner margin. Pronotum widely transverse and broadly explanate, convex anteriorly but flattened towards the basal margin so that in side view the posterior margins are almost level with the disc but above the basal margin, densely sculptured and punctured. Elytra with 3 longitudinal rows of elongate tubercles, each separated by 3 complete longitudinal carinae, otherwise quite finely microsculptured and lacking punctures, lateral margins explanate and roughly sculptured. C. arvensis Herbst, 1784 is similar but consistently smaller, at most 21mm in length and has rather irregular ridges between the longitudinal rows of tubercles, often interrupted or varying in strength. C. granulatus Linnaeus, 1758 is superficially similar and also overlaps in size but here the elytral tubercles are separated by a single longitudinal carina. Male pro-tarsal segments widely dilated.