Cilea silphoides (Linnaeus, 1767)
This is a generally common and often abundant species throughout the Holarctic region except for the far north, it may be native to Europe and North Africa but its origin is uncertain; it has long been established in North America, having been first described from that region by Gravenhorst in 1802, and it is established throughout Africa and Australasia etc. although its presence in the Neotropical region is less well known. Here it is generally common throughout England and southern Scotland though absent from the West Country and most of Wales. Throughout much of its range it is synanthropic and an occasional pest when large populations develop in mills and granaries etc. but in general it is associated with decaying organic matter; compost, decaying fruit, hay, leaf-litter and carrion but especially among decaying fungi and dung where it may occur in very large numbers. Adults occur year-round and are generally active from April until late in the year, they fly well and are quick to colonize new environments e.g. disturbing dung or decaying fungi on warm evenings may attract them within minutes. Locally we have recorded them from recently accumulated grass-cuttings, pond-clearance debris, fungoid bark and old dry horse manure on woodland bridle paths, and from extraction samples of such material through the winter, Numbers peak in July and again in the autumn when they may be very abundant among thousands of other staphs in decaying terrestrial fungi.
Although most specimens are very distinctly coloured these small beetles are easily overlooked in the field; they move quickly and fly readily when disturbed and the elytral pattern is cryptic against dung etc.
2.5-3.5mm. Broadly-oval and convex, forebody and elytra glabrous and lacking long lateral setae. Head shiny black with weak transverse microsculpture, eyes weakly convex and continuous with the outline, antennae 11-segmented; dark with at least the 2 basal segments pale. Pronotum transverse, shiny and dark on the disc and variously pale laterally, surface with transverse microsculpture a little stronger than that on the head. Scutellum large, triangular and microsculptured as the pronotum. Elytra transverse with the sides evenly rounded and strongly bordered, the suture simple i.e. not raised, and distinctly though variably patterned; the disc dark and the margins variously pale although occasionally almost entirely dark specimens occur, finely punctured and rugose but lacking microsculpture. Abdomen very finely punctured and pubescent, black with the posterior margins of the segments variously pale, segments 1-5 with long lateral setae which are outside the raised borders. Legs entirely pale, all tibiae with strong lateral setae and small spurs at the inner apical angle. Tarsi 5-segmented.