Hemicrepidius hirtus (Herbst, 1784)
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POLYPHAGA Emery, 1886
ELATEROIDEA Leach, 1815
DENTICOLLINAE Stein & Weise, 1877
DENTICOLLINI Stein & Weise, 1877
Hemicrepidius Germar, 1839
This generally common species occurs throughout Europe north to mid-Fennoscandian latitudes and south to the Mediterranean, extending east through the Caucasus, Asia Minor, Iran and Russia to western Asia, the ecology and biology are only poorly understood on the continent as it has often been confused with the similar and more common H. niger (Linnaeus, 1758). Here it is our only UK member of the genus, it occurs commonly throughout England and Wales though it is generally absent from the West Country and less common in the north of England, and although it is absent from much of southern Scotland there are records scattered across the Highlands extending north to Orkney; it is generally a species of lowlands in the UK but on the continent extends to mountain altitudes of 2500m in the Alps. Typical habitats are well-vegetated areas in open deciduous or mixed woodland, meadows or cultivated soils, usually bordering woodland but we have recorded them from a wide range of habitats including dry calcareous grassland in the Chilterns on hillsides exposed to the sun, and from lush grass on wet peat-cuttings in Somerset. Adults are active from May to July, extending into August in mountain regions, they are diurnal and occur among grasses, low shrubs and herbaceous plants but they also visit flowers and may be observed on umbels etc. Mating occurs early in the season and larvae develop in a range of habitats; they inhabit soil but also commonly develop within decaying wood or under bark on stumps, dying trees or fallen timber. Larvae are predatory but are also known to feed on decaying plant material, they develop through the summer and overwinter in the soil or in wood, they resume feeding and complete their development in the spring, pupate and produce new-generation adults from May.
This is among the largest of our elaterids and this large size coupled with the entirely black colour should serve to identify the species; members of the genus Melanotus are also large and dark but here the claws are serrate. 9-14mm. Dorsal surfaces with fine pale pubescence. Head transverse, finely and rather densely punctured, with finely-faceted large convex eyes and medially depressed frons, terminal segment of maxillary palps securiform. Antennae serrate from the third segment, second segment much shorter than the first or third, basal segment much longer than the third, terminal antennomere simply elongate, not constricted or produced apically. Pronotum quadrate or slightly elongate, broadest about the middle and sinuate laterally before weakly produced posterior angles, surface rather densely punctured; strongly so anteriorly becoming weaker towards the base, and indistinctly ridged above the posterior angles. Scutellum large, convex and obtusely angled, finely punctured and pubescent. Elytra elongate and curved laterally to a continuously rounded apical margin, striae punctured and complete to the apex; deeply impressed toward the base, especially the third and fourth where they cross the humeral convexity, becoming finer and less impressed apically, interstices weakly convex, finely rugose and very finely punctured. Legs entirely dark or with the tarsi a little lighter; generally at least the claws and the tarsal lobes are pale. Tarsi distinctive; basal segment long and simple, second and third segments with distinct ventral lobes, fourth segment tiny and lying partly within the lobes of the third, fifth segment long and curved. Claws smooth, long, curved and with an obtuse basal tooth.