Tachyporus hypnorum (Fabricius, 1775)
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POLYPHAGA Emery, 1886
STAPHYLINOIDEA Latreille, 1802
TACHYPORINI MacLeay, 1825
Tachyporus Gravenhorst, 1802
This is a common species of lowlands throughout the U.K. north to Orkney and the Western Scottish Islands while abroad it is generally common throughout Europe and North Africa extending east through central Asia to northwest China. Adults occur year-round and are active from the first mild days of late winter or early spring until late in the autumn, they occur in almost any fairly open habitat including wasteland and gardens and are quick to colonize recently disturbed sites. Adults are long-lived, up to a year, and are generally inactive through the winter in the soil or among tussocks or under debris and may occur in numbers among litter under hedgerows etc. although during mild spells they become active and this may adversely affect their survival rates as they search for food and deplete fat reserves, and it seems that survival is highest over cold winters when they remain dormant. Both adults and larvae are predatory although the larvae are also known to consume seeds and fungi on leaves etc. and the species is recognized as having a significant effect on various crop pests; they consume large numbers of aphids and the eggs and larvae of e.g. Delia radicum (Linnaeus, 1758) (cabbage root fly), Oscinella frit (Linnaeus, 1758) (cereal pests) and Lema melanopus (Linnaeus, 1758) (cereal leaf beetles), and are often abundant on arable land during the summer. Following a period of feeding overwintered adults migrate from their winter habitats to more open sites, often grassland or arable land, where mating occurs and oviposition begins, these adults will persist into early summer and then die-off. Eggs are laid in the soil or among litter etc. over a long period from May to June or July and larvae emerge after a week or so, development is rapid and each of the 3 instars are fully grown within 4 or 5 days, pupation occurs in similar habitats and the entire cycle from egg to adult takes about a month. New generation adults appear from June and are soon common almost everywhere; they occur in numbers on vegetation and flowers, especially umbels, and may be swept from grass generally, both adults and larvae are largely nocturnal, climbing stems and trunks in search of prey.
Very distinctive among our small staphs due to the dark colouration, fusiform body and, for the genus, relatively large size; overall, 3-4mm although this is general as the head may be retracted into the prothorax and the abdomen telescoped one way or the other. Head black, smoothly convex and shiny, with large weakly convex eyes and small, straight temples. Antennae long and filiform with all segments elongate, and only weakly broadened towards the apex. Palps yellow or slightly darkened apically, the penultimate segment much shorter than the terminal segment. Pronotum evenly rounded laterally and straight across the base, usually extensively black or very dark with the lateral and basal margins broadly yellow, and usually with 4 long and stiff setae along each side although these tend to get broken in life. Elytra slightly elongate, parallel-sided and curved across the base; mostly yellow and somewhat iridescent but usually dark around the scutellum and lateral margins, punctation very fine and, towards the base, very finely cross-strigose. Sutural margin almost flat i.e. without raised borders, and each elytron with 3 rows, including one adjacent to the suture, of 2-4 very fine erect setae, these may be missing or broken but the punctured attachment sites are visible with strong very low-angle lighting. A similar very fine seta, offset from the rows, is usually present behind the humeral angle but may be missing on one or both sides, and each lateral margin has several very long and outstanding setae. Abdomen evenly tapered to the apex, black and usually with a blue to golden iridescence and the apical margins of segments 1-5 broadly pale, lateral margins strongly raised on segments 1-4 or 5, segments 6 and 7 dark and not, or hardly, raised laterally. Punctation very fine and weakly cross-strigose, becoming sparse or absent towards the apex of each segment. Each segment with a long black seta at the posterior angle and various others laterally. Appendages pale; antennae variously darkened towards the apex.