Carabus convexus Fabricius, 1775
This very widespread Eurasian species is represented by seven subspecies, most are rather local but the nominate subspecies is generally common across Europe from northern Spain to southern Scandinavia and east to the Caucasus, Russia and Siberia although in northern regions it is more local and has suffered a recent decline; it is generally rare in Denmark, rare and legally protected in Poland and probably extinct in the Netherlands although it remains widespread and locally common in southern Sweden. It occurs from lowland to low mountain altitudes and in some central areas e.g. Poland, it is more generally a mountain species, the typical habitat is warm soils in dry locations, often in sandy or deforested areas with patchy areas overgrown with trees and shrubs. Both adults and larvae are nocturnal predators, feeding on earthworms and other insects and their larvae, adults occur year-round and may have a long season, depending on latitude. It is a spring breeder with larvae developing through the summer and new generation adults appearing from July in southern areas and later further north; in southern Sweden they appear in the autumn. Adults are flightless and disperse by walking. In the UK there are a few widely scattered 19th century records from England, it is thought to have been native but is now long extinct.
Although not included in British carabid keys this species may be recognized by its small size, 14-20mm, and broad oval form. Entirely shiny black or with the elytral margin and pronotum variously metallic blue, the pronotum sometimes extensively so. Head roughly sculptured, with convex and protruding eyes and large curved mandibles, the terminal segment of the labial palps is broadly expanded, more so in the male, and the penultimate segment has 2 long setae on the inner margin. Pronotum weakly transverse with narrow lateral margins and depressed before the base, surface entirely and quite strongly rugose. Elytra broadly oval with narrow explanate margins, moderately convex and rather abruptly declined in side view. Each elytron with 3 distinct rows of large punctures between which are numerous longitudinal ridges; across the disc at least 7 between each puncture row.