Orchesia minor Walker, F., 1837
POLYPHAGA Emery, 1886
TENEBRIONOIDEA Latreille, 1802
MELANDRYINAE Leach, 1815
Orchesia Latreille, 1807
This widespread species occurs throughout central and northern Europe, extending south into northern Italy and Romania but absent from the Iberian peninsula and most of the Balkans, it extends north into the UK and the northern provinces of Fennoscandia and to the east it reaches western Siberia through Russia and northern Kazakhstan. In Europe it is very local although more common in mountain areas and towards the east; it is widespread and locally common in England and Wales although less so in the north and most frequent in the south east below London, it is generally absent from Scotland and very local and rare in Northern Ireland. The typical habitat is damp deciduous woodland and carr but adults are very active and can fly well and so may also occur in wooded parkland or on individual trees in wooded pasture, on the continent much more rarely in conifer wood where it has been recorded from dead pine trees. Adults are mostly nocturnal and may be found on the surface of trunks and fallen branches but in hot weather they take flight during the day and visit a range of flowers including umbels and blossom, they are active from March until August or later depending on the season and usually occur as pairs or single specimens but large numbers may occasionally be found in the spring at night swarming over a particular trunk or fallen bough. Mating occurs in spring and early summer and larvae develop in wood invaded by mycelium and in fruiting bodies of various fungi including Hoof fungus (Fomes fomentarius (L.) Fr) and Alder bracket (Mensularia radiata (Sowerby) Lézaro Ibiza). Larvae pupate among dead wood during the summer and new-generation adults are fully developed by September but they remain within the wood until the following spring. The species is thought to be univoltine. Adults have been recorded from a wide range of deciduous trees including beech, hazel, alder, birch, oak, hornbeam, cherry, elm, willow, poplar, lime and rowan and, on the continent, from various conifers including pine, juniper, larch and Norway spruce. They may be sampled by sweeping or by nocturnal searching but they will need to be examined closely for certain determination and catching them can be difficult as they run and jump rapidly at the slightest disturbance.
Orchesia minor 1
Orchesia minor 2
2.5-3.75 mm. Long-oval and more-or-less continuous in outline, entirely dark brown or paler about the anterior pronotal margin and basal and lateral elytral margins, legs pale brown or with darker femora and/or tibiae, antennae pale with segments 6-11 variously darkened. Dorsal surface finely punctured and pubescent throughout, the punctures forming rather random transverse microsculpture. Head smoothly convex, with weakly-convex, reniform eyes and securiform palps. Interocular distance only slightly less than the distance between the antennal insertions. Antennae inserted laterally in front of the eyes, the insertions visible from above, 11-segmented and gradually widened to a long 4-segmented club, the club segments wider but hardly longer than those preceding. Pronotum broadest across the base and evenly narrowed to a rounded anterior margin, posterior angles acute and basal margin slightly produced medially, surface convex with two wide basal fovea. Scutellum partly obscured by the pronotal margin. Elytra elongate, broadest about the middle and evenly narrowed to a continuously curved apical margin, without striae but with a variously developed fine raised line adjacent to the suture, evenly convex and rather flattened with the suture slightly raised towards the apex. Hind legs very robust, the tibiae with two more-or-less equal apical spurs almost as long as the first tarsal segment. Middle tibiae slender, with much smaller apical spurs. Front tibiae slender, with small spurs at the inner apical angle. Tarsi 5-5-4; fourth segment of the front and middle tarsi bilobed, basal segment of the middle and hind tarsi about as long as the others combined.