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Silpha tristis Illiger, 1798







POLYPHAGA Emery, 1886

STAPHYLINOIDEA Latreille, 1802

SILPHIDAE Latreille, 1806

SILPHINAE Latreille, 1806

SILPHINI Latreille, 1807

Silpha Linnaeus, 1758

Recorded throughout Europe north to the UK and the Baltic countries where it extends into central provinces of Sweden, also from Morocco, Turkey, Iran and Western Russia, this species occurs from lowlands to the subalpine zone; it is locally common in central and northern regions but otherwise much more local and generally scarce. The species was accidentally introduced into eastern Canada during the late 20th Century and is now established in Quebec although it records remain sporadic and it does not seem to be spreading. In the UK it is locally common across southern and central England, mostly coastal in the West Country and Wales, and much less common further north into Southern Scotland and around the coast of Ireland. Adults occur year-round; they overwinter in tussocks or among grass roots and are active from March until September or October. The usual habitat is open grassland, heathland and scrub, often on chalky or sandy soils, but adults fly well and have been recorded from a wide range of open habitats including wetlands, salt-marshes and upland moors. Both adults and larvae feed on carrion, including dead insects, worms and molluscs etc. Breeding occurs in spring and early summer, and eggs are laid in soil, usually near to carrion or at sites where larval food is abundant. Larvae pass through three instars within three to four weeks and pupation occurs in a subterranean cell; the prepupal and pupal stages lasting from one to four weeks. Fresh adults occur from mid-summer, usually when the previous generation adults have died; these will feed but will not mate until the following spring. Adults are mostly crepuscular and nocturnal, by day they may be found under stones and matted vegetation in suitable habitats although they are often active on the surface during warm weather and so may be found by chance, at night they often occur in pitfall or carrion-baited traps, and these should be inspected regularly as the beetles may occur in numbers.

Silpha tristis

Silpha tristis

13-17 mm. Elongate and broadly-oval, glabrous and entirely dull black with contrasting shiny elytral ridges, Head transverse and broadest across small eyes that follow the outline, temples curved and narrowed, clypeus narrowed in front of the eyes and smoothly curved anteriorly, labrum widely and smoothly emarginate. Surface finely and densely punctured, sometimes confluently so on the vertex. Antennae inserted laterally in front of the eyes, 11-segmented with a gradual and loose five-segmented club, segments two and three almost equal in length, and the eighth segment at most as long as the ninth segment. Pronotum transverse, widest in front of rounded posterior angles and smoothly narrowed to rounded anterior angles, apical margin curved and projecting to about the level of the anterior angles, basal margin straight across the middle, sinuate laterally, lateral margins strongly bordered. Pronotal surface weakly convex and uneven but without defined depressions, densely and finely punctured throughout. Scutellum large with curved lateral margins and a pointed apex, surface densely punctured; usually a little more so than the pronotum. Elytra elongate and only weakly curved, sometimes almost parallel-sided laterally, explanate margin narrowed from the shoulders and absent before the apex, each with four (including the sutural) strong longitudinal ridges; the second and third often continuing almost to the apex and the fourth angled inwards and fading in the apical third, surface densely punctured; each puncture lying behind a tiny tubercle (easiest seen, along with tiny pale hairs, towards the base at X50) Legs long and robust. Tibiae only weakly broadened from the base, all with longitudinal rows of fine bristles and a long apical spur. Tarsi with five simple segments, except segments 1-4 widely dilated in males. Sometimes confused with the more common Phosphuga atrata, but here the head is more produced and parallel-sided in front of the eyes, the labrum is deeply emarginate, and the elytra are less elongate, more curved laterally and generally shiny so that the longitudinal ridges do not contrast with the rest of the elytra.

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