Tachyporus obtusus (Linnaeus, 1767)
This Palaearctic-wide species is generally common throughout Europe from Portugal to Greece and north to the UK and above the Arctic Circle in Fennoscandia, present on many of the Mediterranean islands although not, apparently, in North Africa, it occurs from lowlands to upper limit of the tree-line in mountain regions. In the UK it is generally abundant in south-eastern England, East Anglia, the midlands and Wales and rather less so further north to the Scottish Highlands and in Ireland. Adults are present year-round and may remain active in all but the coldest winter periods; they are generally active from March or April until the autumn and peak in abundance during May and June. Typical habitats are open grassland, arable land and pasture but adults often occur in damp woodland and on exposed sand or gravel beside reservoirs and streams etc., and during the summer they sometimes appear in gardens and other disturbed habitats. Winter is spent among moss or in litter or tussocks in sheltered situations such as hedgerows or under logs and spring migrations occur when the temperature increases, generally during April, now they fly to open situations where they will breed following a period of feeding. Both adults and larvae predate other small insects and their larvae, particularly aphids and springtails, and, along with various other small staphylinids, they are thought to contribute significantly to pest control in spring and summer arable crops. Breeding occurs in the spring and larvae develop in spring and summer; they have been recorded from June until August and new-generation adults appear over a long season from July until September or October. There is a single generation each year. Both adults and larvae are mostly crepuscular and nocturnal, they are terrestrial and both stages are often found in pitfall traps. Adults may be found by searching under stones or debris or by sieving organic matter etc., they often appear in extraction samples of moss or tussocks during the winter and may appear in numbers in flood refuse at any time.
Tachyporus obtusus 1
Tachyporus obtusus 2
3.5-4.0 mm. Typical specimens are easily identified from the habitus and general colour; head and pronotum orange, elytra orange with the basal third to half abruptly black, abdomen orange with two apical tergites black, antennae pale but variously darkened towards the apex, legs pale. Occasionally the head and pronotal disc are darkened and very occasionally the elytra are darkened only around the scutellum and along the lateral margins. Head smoothly convex and continuous in outline, shiny and unpunctured. Terminal maxillary palpomere elongate and slender throughout. Antennae slender and only slightly thickened towards the apex, with all segments elongate, the penultimate segment only slightly so. Pronotum transverse, broadest behind the middle and narrowed to rounded posterior angles and weakly projecting anterior angles, lateral margin with 2 or 3 fine setae which are about as long as the basal antennomere, surface smooth and shiny. Elytra quadrate to weakly transverse, laterally finely bordered and with 2 or 3 fine setae, suture weakly raised, surface finely sculptured and pubescent and so less shiny than the pronotum. Abdominal tergites finely punctured throughout, lateral margins raised and each with several long setae. Legs long and slender, front tibiae with a single terminal spur, middle and hind tibiae with several rows of stiff setae and two terminal spurs. Tarsi 5-segmented, basal segments of front tarsi broad, terminal segment long and slender, first and fifth segments of middle and hind tarsi notably elongate. Claws smooth and not toothed at the base.