Colobopterus erraticus (Linnaeus, 1758)
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POLYPHAGA Emery, 1886
SCARABAEOIDEA Latreille, 1802
APHODIINI Leach, 1815
Colobopterus Mulsant, 1842
This is among the most widespread and generally common members of the Aphodiinae, it occurs throughout the Palaearctic region from Portugal to the far east of Russia except for the most northerly latitudes, it is also common across North Africa and the Near East and following introductions, supposedly in ship’s ballast, is now widespread across southern Canada and sporadic in the northern United States. Here it is common and sometimes abundant, though less so than formerly, across south east England from Dorset to The Wash and throughout lowland Wales including Anglesey, it is otherwise almost absent from The West Country and sporadic and generally scarce further north to southern Scotland. Adults overwinter in the soil and are active from May until August or September, peaking in abundance during June or July, they typically occur in large herbivore dung on open pasture but individuals may be found in the dung of a wide range of mammals in almost any habitat, especially in spring and early summer when they disperse by flight e.g. we have recorded them from horse dung on shaded bridle paths in local woodland and from deer droppings on calcareous grassland hillsides in the Chilterns. Breeding occurs from June when mating pairs may be seen on the surface of freshly deposited dung, adults then enter the dung and females oviposit at the base of the pat. Larvae develop in brood masses beneath the dung pat, they grow rapidly and when fully-developed burrow into the soil to pupate, adults eclose from late summer and may become active for a while but most will remain in the soil to overwinter. Adults are easily sampled by searching through host material or, in the spring and early summer, netted in flight over dung pasture on hot sunny days; fresh wet dung that has formed a crust will often host several specimens and these often consist of pairs of males and females but while they may be present in every dung sample over a large area they generally occur in small numbers in any individual sample, at least in our experience in South Hertfordshire. Other species of Aphodiinae are often present and we usually find species of Sphaeridium Fabricius, 1775 and Cercyon Leach, 1817 to be abundant within the same sample.
Adults are readily recognized by the large size, 6-9mm, long scutellum and distinctive colouration which is usually obvious even in the field. Forebody and appendages extensively black, elytra dull brown with the sutural interval and base black, head and pronotum finely and rather densely punctured; the punctures varying in size. Clypeus at most only slightly expanded in front of the eyes, strongly bordered throughout and weakly sinuate across the anterior margin, posterior border with a single median tubercle within a transverse ridge, more developed and sometimes bifid in the male. Pronotum transverse and broadest about the base, with evenly curved lateral margins, rounded posterior angles and a weakly sinuate basal border, the surface simply convex in both sexes. Scutellum triangular and sharply pointed, at least one-fifth the elytral length and often longer. Elytra evenly curved from rounded shoulders to a continuous apical margin, striae very narrow and finely punctured, usually fading out before the apex, interstices flat to weakly convex and finely punctured throughout. In most specimens the elytra are pale to medium brown with the suture and base darkened but the sutural line may be wider and there may be various obscure darker markings on the disc, and almost entirely dark specimens occur on the continent. Legs dark but usually with lighter tarsi; front tibiae strongly fossorial, mid and hind tibiae with three external transverse ridges, all tibiae with long apical spurs.