Dasytes niger (Linnaeus, 1760)
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POLYPHAGA Emery, 1886
CLEROIDEA Latreille, 1802
DASYTINAE Laporte, 1840
Dasytes Paykull, 1799
This is a widespread Palaearctic species, extending from Spain through Asia Minor to Siberia and Mongolia, in Europe it occurs from lowlands to about 2000m and is common in, warmer southern and central regions and more local in the north, reaching the UK and to the Arctic Circle in Scandinavia. Here it is restricted to Sussex and Hampshire although there are older records from slightly further north but it may have declined over recent decades, it may be common where it occurs, and adults have been recorded swarming over logs in bright sun, which makes this restricted UK distribution interesting when compared with that of Scandinavia here it occurs more-or-less throughout the region. Adults are active between May and August, peaking in abundance during June and into July; they are diurnal and inhabit open deciduous woodland and parkland with plenty of trees in various stages of decay. The predatory larvae are known to develop through the summer under bark or among decaying wood, they usually occur under bark on smaller branches, up to 20 cm, or in fallen timber up to 40cm in diameter, and have been recorded from a wide range of trees including Birch (Betula L.), Rowan (Sorbus aucuparia L.), Aspen (Populus tremula L.), Willow (Salix caprea L.), Oak (Quercus L.), among others, and on the continent they are also frequently recorded from Pine (Pinus L.) and Norway spruce (Picea abies (L.). Larvae overwinter under bark etc, they pupate in situ in the spring and adults emerge from the wood in May. Adults fly well and visit a range of flowers, especially various umbels and blossom where they feed on pollen, and so can be sampled by sweeping although they also occur on trunks and fallen timber or they may be found by chance; our only experience of the species was when a specimen landed on our car window in a woodland car park in the New Forest in Hampshire.
3.5-4.5 mm. Long-oval and rather depressed, entirely shiny black, without a metallic reflection, finely punctured and with fine erect setae throughout. Head with large, convex eyes and long, converging temples which are usually substantially retracted into the thorax, vertex weakly convex, frons flattened and without impressions. Antennae inserted laterally in front of the eyes, 11-segmented and serrate in both sexes. Pronotum distinctly transverse; about 1.3X wider than long, broadest near the base and with distinct angles, apical and basal margins curved, surface evenly convex, towards each lateral margin with a longitudinal impression which is variable but always distinct in the basal half. Elytra much wider across the base than the base of the pronotum, with rounded shoulders and dilated before separately-curved apical margins, without striae, the surface finely rugose between the punctures pubescence of two types; erect and recumbent but these tend to get mixed. Legs long and slender, the femora widely visible with normal setting. Tibiae long and narrow, each with a very fine apical spur. Tarsi with five simple segments. Front and middle claws with a strong basal tooth in the male. In most Dasytes the eyes are dimorphic, being larger and more convex in the male, but in the present species they are similar between the sexes, the antennae are longer and narrower in the male and the fifth sternite has a wide triangular impression.