Stephanopachys substriatus (Paykull, 1800)
POLYPHAGA Emery, 1886
BOSTRICHOIDEA Latreille, 1802
DINODERINAE Thomson, C.G., 1863
Stephanopachys Waterhouse, C.O., 1888
A boreo-alpine species with an Holarctic distribution; it extends from Europe to Siberia, Mongolia and the far east of Russia and across North America including Canada and Alaska, in Europe it occurs throughout Fennoscandia and is known from the Carpathians, the Alps and the mountains of Yugoslavia and Transylvania. In the UK it is known from only a very few records from southern and central England, probably all from imported timber, although it may have become established. The species is usually associated with extensive conifer forests, often in areas damaged by fire, but it may also occur on individual trees on upland moors and mountain valleys, the usual hosts are pines, spruce and larch but other species have been recorded. Adults are active from June until November, peaking in abundance during July or August, but specimens are occasionally recorded during the winter among non-processed logs and bark in saw mills and tanneries etc. Larvae develop under damaged bark or in sapwood on otherwise healthy trees, they are thought to feed on sap and wood debris and they usually occur in branches between 15 and 25cm in diameter, they probably pupate in late summer and there is a single generation each year although larvae may develop over a second year. Adults are nocturnal but rarely venture out of their galleries; they may be found near protruding bark on dry trunks and branches, they disperse by flight and have been recorded at light and in flight-interception traps. On certain very humid days, usually before stormy weather, they may take flight by day and form dispersal swarms over fallen timber.
3.3-6.5 mm. Elongate and convex, body shiny dark grey or brown, antennae brown, often paler towards the apex, legs brown with paler tarsi. Head broadly transverse, flat and regularly granulate between convex and prominent eyes, cheeks (between the antennal insertions and the labrum) much shorter than the median length of the labrum, fronto-clypeal area depressed but without a distinct suture, labrum wide and narrow, slightly emarginate and with dense yellow setae along the anterior margin. Antennae 10-segmented with a long and loose 3-segmented club. Pronotum quadrate, broadest across the base and narrowed to a rounded apical margin which substantially covers the head between the eyes, basal margin rounded, surface strongly tuberculate anteriorly (these arranged in semi-circles from the middle but this is not always obvious), granulate posteriorly and with scattered tiny yellow hairs throughout. Scutellum expanded from the base and emarginate across the apex. Elytra parallel-sided from rounded shoulders to a continuous apical margin, surface with rows of deep and large punctures, mostly regular but usually confused towards the base, and scattered yellow pubescence which is generally longer over the steep apical declivity. Legs short, with femora hardly visible in normal setting. Front tibiae with small teeth along the external margin, a large external tooth at the apex and a single large and curved tooth on the inner apical margin. Middle tibiae with five or six external teeth and a single apical spur. Hind tibiae with two external teeth, one before and one at the apex, and a single apical spur. Tarsi 5-segmented; the basal segment diminutive and the apical segment long and thickened towards the apex. Claws smooth, without a basal tooth.