Cercyon quisquilius (Linnaeus, 1761)
POLYPHAGA Emery, 1886
HYDROPHILOIDEA Latreille, 1802
SPHAERIDIINAE Latreille, 1802
CERCYON Leach, 1817
CERCYON Leach, 1817
A widespread native Palaearctic species occurring throughout Europe and Asia to the far north of Scandinavia, across North Africa and Asia Minor, it is now Holarctic having been introduced into North America around 1920 it now occurs across southern Canada south to Mexico and, following more recent introductions, is established widely in South America, southeast Australia and on many oceanic islands including Hawaii and through much of the Caribbean. In the UK it is widespread and generally common across England and Wales, although seemingly absent from the West Country, and sporadic in southern Scotland. Throughout Europe it occurs from lowland to subalpine altitudes. They are coprophagous but will also develop in a range of decaying organic matter e.g. compost or decaying fungi; they have been found in bird nests and we have found them among decaying carrion in a Watford reed bed, the typical habitat is dung pasture where they are active from early spring to late autumn and occasionally through the winter; they overwinter in the soil below dry dung and become active very early in the year when they may be found in old and dry dung samples. By April they are common in a wide range of dung but cattle and horse seem to be preferred and they will appear in most situations e.g. they are common in horse dung on bridle paths in local woodlands, they fly readily and will soon appear in new habitats. Numbers peak in June and July when they may be observed on warm days alighting on dung or emerging and taking flight, they generally fly in the afternoon but mass dispersal occurs at night when they may appear in large numbers at light. Fresh dung will attract them within minutes and they remain until it has been consumed or dried out; lifting old and dry samples will often reveal the beetles embedded under the crust or among dry dung at the soil surface.
This tiny species will soon become familiar from its elongate form and colouration. 1.9-2.6mm. Elongate-oval and convex, in lateral view continuously curved from the head to the elytral apex. Upper surface glabrous and shiny. Head shiny black and moderately strongly punctured but without microsculpture (X50), eyes weakly convex and continuous with the outline, labrum and mouthparts pale. Maxillary palps as long as the antennae and pale or darker apically. Antennae pale with the club dark. Pronotum black in mature specimens but usually narrowly pale laterally, broadest at the base and finely bordered, shiny and punctured as the head. Scutellum elongate, shiny black and punctured as the head. Elytra entirely testaceous or with a large triangular mark around the scutellum, suture and punctures within the striae darker. Surface shiny, becoming dull towards the apex, striae 1-9 complete and well-impressed and punctured to the apex, ninth stria distinctly less strongly punctured and evanescent about the middle interstices flat and very finely punctured. Legs pale; pro-tibiae rounded apically, all tibiae with stiff spines along the external edge. Meso- and meta-tibiae with a pair of long stout spurs at the inner apical angle, pro-tibial spurs tiny. Tarsi 5-segmented; basal meso- and meta-tarsomere much longer than the second segment. More elongate and less curved laterally than other small and pale dung Cercyon although C. unipunctatus (Linnaeus, 1758) is similar in shape but generally characteristically coloured.