Emus hirtus (Linnaeus, 1758)

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POLYPHAGA Emery, 1886

STAPHYLINOIDEA Latreille, 1802

STAPHYLINIDAE Latreille, 1802

STAPHYLININAE Latreille, 1802

STAPHYLININI Latreille, 1802

Emus Leach, 1819

This very conspicuous species occurs throughout Europe, from lowlands to high altitudes, from Spain north to Scandinavia and east through Asia Minor to Russia. In the U.K. it was formerly widespread although extremely local in the south of England but seems now to be confined to north Kent and south Essex either side of the Thames estuary. On the continent it is a local insect of sandy, generally open habitats and open wooded areas and clearings. There has been a Europe-wide decline since the 1960’s but there now seems to be a general increase in records. The adults may be abundant where found and are very active; they run rapidly and adopt the typical staphylinid defensive posture when alarmed, with the head and abdomen raised and the mandibles open. They fly readily and resemble a large humble bee in flight. The adults are active from April to October with a peak of activity in mid-summer. Mating occurs in mid- or late-spring and larval development is rapid; pupation occurs in mid-summer and new generation adults are active in late summer and autumn. Both the adults and larvae feed upon various insects but the adults seem to be specialist predators of Aphodius species. The adults are strongly attracted to horse and cattle dung where, on arrival, they will run rapidly over the crust inspecting any crevices or holes for the presence of other beetles; when found they are pulled from the dung, turned onto their backs and dismembered, generally the head is bitten off before they are consumed. Although generally occurring on open and bright dung pasture they also inhabit other dung including that if sheep, goat and deer etc. as well as being occasionally found among carrion or compost, all habitats rich in insects and their larvae. There is little evidence as to where the adults overwinter but it is thought that they move from open situations to marginal habitats in lightly wooded areas. In Europe the adults have been reported entering hymenopteran nests.

Emus hirtus

Emus hirtus

Emus hirtus

Emus hirtus

Emus hirtus

Emus hirtus

At up to 30mm in length this is one of our largest staphylinids; the size along with the colour and pattern of the dorsal pubescence will serve to identify the species. The entire upper surface is finely and densely punctured, the cuticle being shiny beneath the pubescence. The head is a little transverse and, due to the expanded temples, as wide as the pronotum. The eyes are round, not notched, and form the anterior angle of the head, the labrum is transverse and deeply notched and there is a distinct neck although this is generally obscured by pubescence. The antennal insertions are in front of the eyes and above the inner margin of the mandibles; the antennae are geniculate with the basal segment long and straight, 2 short, 3-5 rounded and 6-11 transverse, the terminal segment sub orbicular and depressed at the apex. The mandibles are robust and well-developed, sharp and with large teeth at the centre of the inner margin. Scutellum large and triangular. Pronotum subparallel in the front half then strongly narrowed to a short and weakly curved hind margin, the front margin is curved in front of distinct front angles. Elytra broader than the pronotum, quadrate or nearly so and parallel or weakly dilated posteriorly. The basal abdominal segments are strongly bordered. Legs short and robust, the anterior coxae are large and the meta-trocanter produced into a large and curved spine. All tibiae have strong apical spurs, and the meta-tibiae are strongly curved inwards towards the apex. Tarsi short and robust with segments 1-4 dilated, very strongly so on the pro-tarsi. Claws smooth and curved. In the male the head is relatively broader and the abdomen narrower and less tapered when compared with the female.

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