Philonthus splendens (Fabricius, 1793)
This is the type species of the genus; it is generally common from lowland to mid-mountain altitudes throughout Europe from the Mediterranean to the UK and the far north of Fennoscandia and extends east through Russia and Asia Minor into Siberia, China and Korea, it is present on many Mediterranean islands and is also known from north-west Africa. Here it is common and often abundant across England and Wales and more sporadic and scarce further north to the Scottish Highlands and the Outer Hebrides. The species is usually associated with herbivore dung and so is common among cattle and sheep dung on open grazing pasture but it may also occur in other situations e.g. among horse droppings on bridle paths and much less frequently among decaying organic matter such as compost or carrion rich in prey such as fly larvae, in northern Europe it is also common among wild animal droppings in deciduous and coniferous woodland. Adults occur from April until October or November, peaking in abundance during spring and late summer, they probably overwinter in the soil but are rarely found at this time other than among flood-refuse. Both adults and larvae are predaceous, the larvae develop rapidly in spring and early summer predating other insects, but especially diptera larvae, among dung etc. while adults are more general predators. Both stages may be found by using dung extraction techniques but the adults are very active and will soon be encountered when working dung, they fly to freshly deposited dung in numbers and soon become buried within or under the dung, when disturbed they sometimes take flight but more usually run rapidly and become lost among the dung or in the ground beneath, they also become cryptic as they move and so can be difficult to sample. Flight-interception and pitfall traps will often produce adults in numbers but these can be very destructive in such situations and so are best avoided.
Philonthus splendens 1
Philonthus splendens 2
10-16 mm. A large and robust rove beetle (on average the largest member of the genus) with a near-parallel forebody and long and gradually tapering abdomen. Glabrous but for the usual sensory setae, forebody, abdomen and appendages shiny black, elytra strongly contrasting metallic green or bronze. Head transverse, more so in the male, with weakly convex eyes and parallel temples which are strongly rounded to a broad neck, surface rather flattened and with scattered micropunctures and large setiferous punctures, especially behind the eyes, and fine linear microsculpture which is often absent from the disc. Antennae inserted anteriorly within the outer margins of the mandibles, segments 1-3 elongate, 4 & 5 quadrate and 6-10 transverse; 9 and 10 strongly so. Pronotum transverse and curved laterally (but not narrowed) to distinct anterior angles, posterior angles obtuse but sometimes continuously-curved to a rounded basal margin, with larger setiferous punctures around the margins but without longitudinal series of punctures on the disc. Scutellum large, triangular and punctured and pubescent as the elytra. Elytra quadrate, slightly broadened towards the apex and with strongly curved apical margins, moderately strongly and densely punctured and pubescent. Abdomen with strongly raised lateral borders, tergites shiny, without microsculpture, finely punctured and with long pubescence, transverse lines at the base of the tergites wavy or simply curved but not angled. Legs long and robust; tibiae with series of strong spines, especially in the apical half, tarsi 5-segmented and simple, the basal segments of the front tarsi transverse. The sixth sternite of the male has a notch on the apical margin but they are usually easily recognized by the more broadly transverse head when compared to females.