Staphylinus Linnaeus, 1758
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POLYPHAGA Emery, 1886
STAPHYLINOIDEA Latreille, 1802
STAPHYLININI Latreille, 1802
S. caesareus Cederhjelm, 1798
S. dimidiaticornis Gemminger, 1851
S. erythropterus Linnaeus, 1758
In the widest sense this is a worldwide genus of about 130 species, it has been extensively revised over the years but remains a difficult group to define even after many species have been removed and assigned to other genera such as Platydracus Thomson, C.G., 1858, Dinothenarus Thomson, C.G., 1858 or Ocypus Leach, 1819, to name but a few of the more familiar. In a more modern sense it includes about 50 Palaearctic species, those from other areas being re-assigned, and the majority of these are confined to Europe; a few extend into western Asia, Asia Minor or North Africa, and only a single species, S. daimio Sharp, 1889, occurs in the far east, including Japan. Even so there is no complete agreement about many of the species; there are undoubtedly 7 ‘good’ species and of course there will be many more but further work needs to be done with the group. Only 4 of the European species are widespread and of these 3 extend into the UK, the fourth, S. rubricornis Ādām, 1987 occurs in south-eastern Europe, extending into the south of Germany and Turkey. Of the remaining species most have very restricted distributions and many are endemic to certain countries e.g. to Germany (14 species), France (13 species), Austria (3 species) or Denmark (7 species). Most species occur in rather damp habitats; adults are mostly diurnal and both adults and larvae are predatory on other insects etc. They are generally only rarely encountered but adults may sometimes be seen running on pathways etc. during warm weather, they should otherwise be searched for under stones or among decaying organic matter rich in prey, and they frequently occur in pitfall traps. Adults are rarely encountered in numbers; they seem to be solitary insects which are likely to be under-recorded. The biology is largely unknown but larval behaviour of some species has been studied, see S. caesareus below.
The large and robust adults are readily recognized among our fauna and with a little experience should be obvious in the field. 14-22 mm. Body black or dark brown, elytra red (in UK specimens), legs pale brown to reddish-brown and antennae pale at the base but darkened apically. Dorsal surface distinctively pubescent; the golden or yellow patches at the front of the head between the eyes and the base of the mandibles are diagnostic among our staphs and there are patches of similar pubescence at the base of various abdominal tergites. Forebody densely but rather finely punctured. Head quadrangular and not dilated or produced posteriorly behind the eyes (c.f. Platydracus Thomson, 1858), mandibles robust and strongly toothed internally, antennal segments not strongly transverse, at most only gradually widened from the base. Pronotum quadrate or slightly elongate, near-parallel-sided with rounded anterior angles and an almost circular basal margin, surface rather flat and often with patches of golden pubescence which can be diagnostic, lateral margin visible from above from the base to the middle where it is reflexed ventrally. Elytra quadrate or almost so, lacking striae and densely and finely punctured and pubescent. Abdomen strongly bordered and variably pubescent but at least the fourth and fifth tergite with lateral patches of golden hairs. Legs long and robust; the tibiae with stiff setae and well-developed terminal spurs. Tarsi 5-segmented, the four basal segments of the front tarsi strongly dilated, otherwise simple.
S. erythropterus Linnaeus, 1758
This is the most widespread member of the genus; it is locally common from lowland to subalpine altitudes throughout Europe with the exception of the Iberian Peninsula and the most northern parts of Fennoscandia, and extends east into Asia Minor and Russia as far as Siberia, it is sometimes quoted as occurring in North America but this seems not be in error, the nominate subspecies occurs throughout this range while ssp. springeri Muller, J., 1923 has a very restricted south-eastern distribution. In the UK it is widespread but rather local and sporadic throughout England and much of Ireland but much more frequent in Wales and Scotland, including Anglesey, Man and the Scottish Islands north to Orkney. The species is rather eurytopic; during the warmer months it may be encountered on pathways or even in parks and gardens in warm weather but in general it prefers open and moist habitats, often on sandy or poor soils with patchy vegetation, wet meadows and wetland margins generally. Adults are often active in bright sun but otherwise might be found under stones or logs or among moss and decaying litter, they are attracted to decaying material generally and have also been recorded from dung and carrion. This is our most widespread and common species and adults have been recorded throughout the year, peaking in abundance in spring and autumn.
14-18 mm. Easily recognized among our members of the genus by the golden-yellow pubescence covering the scutellum, other species may have yellow hairs around the margins but the scutellum is otherwise substantially covered with black hairs. Forebody black, elytra red or reddish-brown, abdominal tergites black with lateral patches of bright yellow pubescence to segments three (which may be narrow and hidden beneath the apex of segment two) and six to eight. Legs entirely red, antennae dark with two or three pale basal segments. Specimens of ssp springeri from higher altitudes have entirely dark legs and antennae. Head transverse (excluding the mandibles) with widely-rounded temples which are much longer than the eyes, surface closely and in places confluently punctured and with cellular microsculpture, especially towards the margins, pubescence sparse and inconspicuous but for the anterior patches. Antennae slender with all segments elongate or the distal segments may be quadrate or slightly transverse. Pronotum slightly elongate, broadest behind rounded anterior angles and narrowed to a curved basal margin, surface densely punctured and finely microsculptured but for a variable smooth median line, pubescence dark, short and inconspicuous. Elytra quadrate or slightly transverse and only weakly dilated towards the apex, surface densely punctured and rugose; the punctures sometimes inconspicuous, and covered with recumbent yellow pubescence. Abdomen usually somewhat dilated about the middle, basal tergites strongly bordered, surface moderately densely punctured, densely pubescent and with conspicuous cellular microsculpture.
S. dimidiaticornis Gemminger, 1851
Although widely distributed and occurring from lowland to sub-alpine regions, this species is generally very local and uncommon, being more frequent across the north of a range that includes most of Europe from the Pyrenees to Ukraine and north to the UK and some southern provinces of Fennoscandia, it extends sporadically east as far as Kazakhstan but is absent from Asia Minor and North Africa. In the UK it is a very local species of Wales and southern England although it is generally absent from East Anglia and much of the West Country, it is present on Anglesey and Man and widespread in the central and western Highlands of Scotland but absent from the Scottish islands, and there are a very few records from southeast Ireland. Little is known of the biology but in the UK adults generally occur in open and damp situations with patchy vegetation while in northern continental areas they are more typical of damp woodland margins and upland meadows. Typical of the group, adults occur among moss and under stones; they have been recorded running on hot summer days and have also been beaten from low foliage of both deciduous and coniferous trees on wooded margins.
16-23 mm. This large and very distinctive species may be distinguished from S. erythropterus by the black pubescence covering most or all of the scutellum and all of the temples, and the strongly darkened distal antennomeres. Forebody black, elytra red to pale chestnut-brown, abdomen black with bright yellow pubescence across the apex of the third tergite (usually the first visible segment) and lateral patches on tergites four to eight, legs and palps red, antennae pale becoming darker apically. Head transverse with rounded and slightly converging temples that are about as long as the eyes, surface densely punctured and sparsely pubescent, anteriorly with bright yellow pubescence in two patches or continuous between the antennal bases, neck with dense recumbent yellow pubescence. Basal antennomeres elongate, 4-7 progressively less so, and 9-11 distinctly transverse. Pronotum elongate and almost parallel-sided, with more or less distinct anterior angles and a rounded basal margin, surface densely punctured but for a narrow median strip that extends from the base into the apical half, pubescence short and dark except for a yellow fringe on the basal margin and a variable yellow patch towards the apical angles. Elytra slightly transverse and weakly dilated from rounded shoulders, surface with short pubescence and fine punctures which are often obscured by the finely rugose structure. All abdominal tergites with dense cellular microsculpture and short dark pubescence as well as yellow markings as described above.
S. caesareus Cederhjelm, 1798
With the exception of Portugal and Spain this species occurs throughout Europe except for the far north and extends east into Asia Minor and western Russia, it is sometimes also quoted as occurring in North America but this seems to be in error, it is locally common throughout this range but more so in the north and seems to be increasing in abundance in some central and northern countries. The nominate subspecies occurs throughout Europe while ssp. corporaali Saint-Claire Deville, 1927 is confined to the French and Spanish Pyrenees. In the UK it is a very local and rare insect with widely-scattered and often coastal records from England and Wales, and it has also been recorded from Ireland. The species is very thermophilic and tends to inhabit open grassland and moorland, especially on hillsides etc. exposed to the sun, and in central Europe it is often common at low mountain altitudes, but more generally it has been recorded from woodland margins, dunes and vegetated shores. Adults occur year round, peaking in abundance from May until July, they are active over a long season from early spring and have frequently been recorded during the winter, they predate fly larvae etc. and so are often associated with dung and carrion but they also occur among compost and leaf-litter and may be seen in the open on warm sunny days. Mating occurs in the spring and eggs are laid directly into the ground, larvae emerge after only a few days but they spend most of their time underground. Each larva will dig a small hole and remain there for most of its life, predating ants and other insects that pass by, they pass through three instars and are fully developed within two or three months, at which time they pupate in an underground cell. New generation adults appear during the summer but they will not reproduce until they have overwintered.
18-23 mm. Distinguished from S. erythropterus by the predominantly black pubescence to the scutellum, any yellow hairs being confined to the margins, very similar to S. dimidiaticornis in most respects, with the same patches of yellow pubescence to the head, pronotum and abdomen, but distinguished by more-or-less entirely pale antennae (the terminal segment only slightly darker than the basal segments), the mixture of black and yellow pubescence around the temples and the lack of dense yellow pubescence to the neck.
