Nemozoma elongatum (Linnaeus, 1761)
This is a generally common species in southern and central Europe which extends very sporadically north to the UK, southern Norway and central Sweden and Finland; it also occurs in North Africa from Tunisia east to Syria and extends east into Ukraine and Russia. Here it is a very local and rare insect of southern and central England north to Nottingham but there are very few modern records and its status is unknown. The typical habitat is established woodland with plenty of old decaying timber, in the south and in lowland situations generally in deciduous species but at higher altitudes and in the north mostly in conifers; both adults and larvae live under bark and are associated with the galleries of other beetles, especially scolytids and ptinids, on which they prey. There is a single generation each year with larvae developing through the summer under bark, on the continent they have been observed feeding on larvae and pupae of Scolytus spp. and Hypoborus ficus Erichson, 1836 (both Scolytinae). Adults have a long season, from very early in the year until October or November, although records from late in the year probably represent new-generation adults which will overwinter and become active early the following year, they peak in the spring, between April and June, and disperse by flight during the day, often forming swarms in woodland situations but where they are common, at least in southern Europe, may be found on fences and houses etc. Adults are generally nocturnal and need to be looked for on the surface of wood but they have also been sampled in flight-interception and alcohol traps, at least on the continent.
This small but very distinctively shaped and coloured beetle should not be confused with any other UK species. 4-6mm. Elongate and parallel-sided, glabrous and entirely black but for the base of the elytra and variable subapical areas pale, appendages pale or with the femora a little darker. Head as wide as the pronotum, deeply cleft anteriorly and smooth but for a longitudinal groove on the clypeus, with well-defined and elongate punctures and very weekly convex eyes, temples and cheeks longer than the eyes when viewed from above. Mandibles very robust; roughly triangular with curved external margins, bluntly-toothed internally and strongly bifid apically. Antennae short; 10-segmented with a loose 3-segmented club. Pronotum elongate and finely bordered laterally, lateral margins finely bordered and apical margin with s fringe of recumbent pale pubescence which overlaps the head, surface strongly and rather sparsely punctured. Elytra with broad and perpendicular shoulders, parallel-sided and continuously curved apically, randomly and quite strongly punctured and with a short longitudinal impression adjacent to the suture before the apex but otherwise without striae. Legs short and slender, the femora only narrowly visible from above, tibiae gradually widened towards the apex; pro- and meso-tibiae with several small external spines, metatibiae smooth externally. Tarsi slender, without lobed segments, the terminal segment almost as long as the others combined.