Creophilus maxillosus (Linnaeus, 1758)
This is a widespread and generally common species with a Holarctic distribution; 2 subspecies are recognized, C. m. maxillosus s.str. occurs throughout the Palaearctic from the west of Europe to the far north of Scandinavia and Japan and, following early 20th century introductions, now occurs in eastern parts of Canada and the United States while C. m. villosus (Gravenhorst, 1802) occurs throughout the Nearctic region and extends south to Chile, Argentina and Peru. The subspecies differ most obviously in the colour of the pubescence on the temples; in maxillosus s.str. it is dark whereas in ssp. villosus it is pale yellow, they are otherwise very similar. The Palaearctic subspecies occurs throughout the U.K. but it is local and not particularly common, but on the other hand the adults are illusive and so the species may be under-recorded. Both adults and larvae are predatory, feeding upon insects and their larvae, particularly those of diptera, in a variety of habitats, and they are also scavengers, feeding upon the decaying remains of carcasses to which adults are strongly attracted. They are likely to appear in any situation where suitable host material i.e. decaying organic material supporting a population of diptera larvae etc. occurs e.g. gardens, pasture, woodland, dunes and all types of marginal habitats including the seashore; we have recorded them on a dead Pike buried in reed litter and from deep within piled and rotten, almost liquid, seaweed alive with diptera larvae, a truly disgusting habitat. Typically they will occur on carcasses, among compost or accumulated vegetation generally as well as among decaying terrestrial fungi in the autumn, and occasionally on dung. The adults are very illusive; they will often be seen on top of, or running around, host material in search of prey but when disturbed they will either run very rapidly into or under the host, into cracks in the soil or among adjacent vegetation, take flight, or employ a defence mechanism where they suddenly roll into a ball and remain still for a while. When threatened they will often be seen to adopt a defence posture with the head and abdomen raised toward the threat, and here they may secrete a defence fluid (dihydronepalactone) while rapidly rotating the abdomen, a behaviour which seems to be particularly effective against ants. Adults occur year-round and are active from early spring
until October or November, being most common in the spring; they generally arrive at carrion a few days after it has been infested with dipteran larvae etc. and they will continue to show interest for as long as these are present. The life-cycle is brief with the period from freshly laid eggs to the eclosion of adults being 5-6 weeks under good conditions. Small creamy-white eggs are laid in soil under or around the host and the larvae emerge within about 4 days. Like the adults they are both predatory, feeding on a wide range of insects etc. as well as scavengers, consuming the host material directly, and they develop quickly, being full-grown after about 2 weeks. They pupate in a cell in the soil either under or away from the host and adults eclose after 2 or 3 weeks. So far as is known there is a single generation, usually commencing in the spring, in temperate regions. Adults may fly long distances in search of host material and are very distinctive when seen flying above dung pasture etc. or along wooded margins in bright sun, they are also crepuscular and nocturnal, being occasionally recorded at light.
At 15-22mm this is one of the largest U.K. (and European) rove beetles; this large size, robust form and very distinctive pattern of pale grey pubescence are unmistakable, the only other large and pubescent species being the equally distinctive Emus. The head is widely transverse with relatively small and flat eyes and long, curved temples, the vertex is finely punctured and mostly glabrous but with sparse setiferous punctures behind the eyes. All appendages are black; the antennae are short and stout with the segments becoming more transverse towards the apex. The mandibles are broad and strongly toothed internally in the basal half, and slender and sharply pointed towards the apex. The pronotum is shiny black, mostly glabrous and lacks any large punctures on the disc; broadest just behind sharp anterior angles and evenly narrowed to a rounded basal margin, all margins are strongly bordered. The scutellum is large, triangular and densely pubescent. Elytra quadrate with prominent, angled shoulders, pale pubescence forming various characteristic transverse bands, the surface finely punctured and each with a longitudinal row of 6-8 strong punctures which are generally visible through the pubescence. Abdomen with pale pubescence forming a symmetrical and generally transverse pattern but this varies widely, and specimens may lose this with age. The head shape is sexually dimorphic; in the female it is more tapered from the basal angles to the mandibles.