Laemophloeus monilis (Fabricius, 1787)
This is the type of a genus of about 30 species, the genus is Holarctic and also extends south into the New World tropics, the greatest diversity is in the New World; fifteen species occur in central and South America, ten in North America (with several occurring throughout) and only four occur in Europe. The present species is widespread across Europe extending north to the UK and southern parts of Norway and Sweden although it is generally very local and rare, to the south it occurs in North Africa and the distribution extends into Asia. Here it is a very rare insect of southern and central England, inhabiting established deciduous woodland and parkland where it is primarily associated with beech but also occurs on oak, sycamore and lime. Adults are present year-round, peaking in June and October, they occur under tight-fitting decaying and mouldy bark on standing and fallen trunks and branches, often near the cut ends of logs etc, and often in company with other subcortical species. The life-cycle is univoltine with larvae developing through the summer, they have been observed feeding on decaying bark and xylem but usually occur among or near to fungi and are recorded from Marchandiomyces quercinus (J. Erikss & Ryvarden) This is a widespread though very local and generally rare fungus in the UK and is restricted to oak. Larvae pupate under bark towards the end of summer and new generation adults appear in late summer and autumn.
Adults are small, 2.5-4.5mm but very distinctive; unique among the UK Laemophloeidae in having a well-impressed and distinct frontoclypeal suture but otherwise unmistakable on general habitus. Males are distinguished by the broader and flatter head and larger mandibles. Body and appendages glabrous; shiny pale to mid-brown, elytra dark brown to black, each with a large semicircular pale macula in the basal half, forebody evenly and very finely punctured. Head transverse with small weakly convex eyes and converging temples, labrum produced and rounded anteriorly, mandibles robust, curved and bifid apically. Antennae inserted laterally in front of the eyes, 11-segmented with all segments, except for the small second segment, elongate. Pronotum transverse and only slightly wider than the head in the male, much more so in the female, broadest behind obtuse anterior angles and narrowed to sharp perpendicular posterior angles, apical and basal margins flat, lateral margins with two or three obtuse teeth which are sometimes rounded and hardly visible, surface each side with a curved sub-lateral carina. Scutellum large and triangular. Elytra with distinct shoulders and curved laterally to a continuously curved apical margin, each with four very narrow striae which begin in the basal half and continue to the apex, the third and fourth united inside the shoulders, interstices randomly and very finely punctured. Legs relatively long with broad femora widely visible from above, tibiae sinuate and only weakly broadened to truncate apices, tarsi 5-segmented but appearing 4-segmented owing to the tiny basal segment, segments 2-4 small and elongate, terminal segment long and curved.