Hallomenus binotatus (Quensel, 1790)
In common with most saproxylic species, Hallomenus has suffered from human habitat modification and has declined over recent decades but it remains locally common though sporadic across the entire Palaearctic region from Spain to the east of Russia and is also native to Nova Scotia, in Europe it occurs from lowland to middle mountain altitudes and extends north to the UK and northern parts of Fennoscandia. In the UK it is locally common across Wales and England north to Nottingham, although it is generally absent from the West Country, very local and scarce further north to the Scottish Highlands, and absent from the Islands and from Ireland. The typical habitat is old woodland and wooded parkland where they are associated with fruiting bodies of a range of fungi, they occur on a range of deciduous trees, and more rarely on various conifers, although in northern latitudes they often occur in pine plantations. Adults occur through the spring and summer, they are nocturnal and spend most of their time on standing and fallen dead timber, usually in the vicinity of fungi but they also visit sap and sometimes in numbers, and they are occasionally active on bark in very warm weather. Eggs are laid in batches into the fruiting bodies and larvae develop through the summer within the fungi, winter is passed either in the pupal or adult stage as adults have been recorded under bark in January in northern continental latitudes, the most frequent host fungus is Laetiporus sulphureus (Bull.)Murrill (1920), usually on oak or beech, but other hosts include Phellinus igniarius (L.) Quel. (1886), often on willows but also birch and alder, P. pini (Brot.) Bondartsev & Singer, (1941), on pine and other conifers, Bjerkander adusta (Willd.) P.Karst. (1880), on a range of dead trees, Polyporus squamosus (Huds.) Quelet (1886), usually on elm or birch, Amylocystis lapponcia (Romell) Bondartsev & Singer (1944), a rare species of coniferous forests, and Pleurotus porrigens (Pers.) Singer (1947) on a range of conifers but usually hemlock. Larvae often occur in large numbers within the fungus and it is unlikely they will have room to overwinter either when fully grown or as pupae, and it is likely that full-grown larvae enter the soil to pupate in the autumn and winter is passed in the adult stage but the details are not understood. Adults are easily found by nocturnal searching but they can move very quickly as well as jump as so will need to be sampled carefully, they may also be attracted to fermenting-fruit traps or sap, and they have been recorded from pitfall traps buried in accumulated wood fragments in old deciduous trees hollows.
3.5-6.0mm. Elongate and narrow, entirely dark to pale brown and usually with the pronotal margins and elytral humeri paler, legs pale brown and antennae variable but usually extensively dark with the two basal segments and the apical segments at least to some extent paler, upper surface finely punctured and with short, pale recumbent pubescence. Head broadest across large and convex eyes, evenly convex and rounded anteriorly, terminal maxillary palpomere long, pointed and about as wide as the penultimate segment, antennae 11-segmented and filiform, the second segment small and quadrate, the others elongate. Pronotum broadest in front of perpendicular posterior angles and narrowed to a rounded anterior margin, the surface evenly convex but for two well-impressed basal fovea, basal margin widely and weakly sinuate. Scutellum transverse, with sinuate lateral margins and rounded apically. Elytra with rounded shoulders, near-parallel in the basal half and gradually narrowed to separately rounded apical margins, without distinct striae but with parallel weak and often incomplete longitudinal impressions that are usually distinct in the basal half. Legs long and slender with all femora visible in normal setting, tibiae only weakly expanded from the base, unarmed and each with a pair of small apical spurs that are much shorter than the corresponding first tarsomere. Tarsi 5-5-4. Basal segment of front and middle tarsi only a little longer than the terminal segment, basal segment of hind tarsi longer than the others combined. This species is rather nondescript and might be mistaken for some melandryids but the size, coupled with the habitus and tiny tibial spurs, are distinctive.