Eucnemis capucina Ahrens, 1812
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POLYPHAGA Emery, 1886
ELATEROIDEA Leach, 1815
EUCNEMINAE Eschscholtz, 1829
Eucnemis Ahrens, 1812
This widespread western Palaearctic species occurs mostly in southern areas from the Pyrenees to Asia Minor and east through Ukraine and Russia into western Siberia, it also occurs in Algeria, and in some countries e.g. France it is locally common but further north it is generally sporadic and scarce, reaching the UK and southern parts of Fennoscandia where it is considered vulnerable. There are very few modern records from the UK and all are from old relic forests in Hampshire, Berkshire and the Cotswolds. Adults occur between May and August and are associated with dead trees or fallen timber; in the UK most records are from beech (Fagus sylvatica L.) and ash (Fraxinus excelsior L.) but on the continent also from oak (Quercus L.), lime (Tilia L.), poplar (Populus L.), sycamore (Acer pseudoplatinus L.), birch (Betula pendula Roth), alder (Alnus Mill.), hornbeam (Carpinus betulus L.) and willow (Salix L.) as well as a range of fruit trees and, from Poland, there is a record from silver fir (Abies alba Mill.) They are mostly nocturnal but will sometimes run in numbers on the surface of fallen branches during the warmest summer days, they fly well and have been recorded at light but in general they will need to be looked for at night, they tend to remain under bark or in crevices and are difficult to find and many European records are from adults emerging from samples of wood taken from known sites, they have also been found on several occasions inside tinder fungus (Fomes fomentarius (L.) Fr. 1849) growing on dead wood. Larvae develop in soft and moist wood or under bark in hollows or trunks of live or recently fallen trees or timber; they develop through spring and early summer and pupate in soft wood or under bark from August. This species is fairly unusual among saproxylic beetles in that the pupae overwinter, adults form in the spring and emerge from the wood during May. The development is usually completed over two years but larvae have been known to overwinter and continue developing into the following summer before they pupate.
4.0-6.5mm. Very suggestive of an elaterid but easily distinguished by the lack of elytral striae. Elongate-oval, body entirely black, often with a bluish or greenish reflection, and moderately strongly and densely punctured and pubescent, legs brown with paler tarsi, basal antennal segments dark, distal segments red or at least reddish. Head with a fine medial longitudinal keel, otherwise smoothly convex between weakly convex eyes, antennae separated by a little more than the length of the first segment, segments 1 and 3 elongate, segment 2 tiny and easily overlooked, segments 4-10 transverse; the strongly serrate appearance of segments 6-10 is characteristic of this species among the UK fauna, terminal segment elongate-oval. Pronotum from above continuously rounded from strongly produced acute posterior angles (the anterior angles are obvious from the side or below), surface depressed medially about the base but otherwise evenly convex. Anterior margin of prosternum straight, front coxae separated by a long triangular prosternal process that extends to the anterior margin of the middle coxae. Metasternum with lateral longitudinal grooves to accommodate the middle tarsi, and produced into triangular plates which cover the base of the hind femora. Scutellum transverse, straight across the base and rounded apically, the surface very finely wrinkled and punctured but appearing smooth against the large pronotal and elytral punctures. Elytra broadest across the base and smoothly narrowed to a continuously-curved apical margin, surface without striae but with several shallow longitudinal impressions that extend from behind the base almost to the apex. Legs short and slender with flattened tibiae and 5-segmented, simple tarsi. The sexes may be determined by the colour of the dorsal pubescence, dark in the male and yellow in the female.