Xantholinus longiventris Heer, 1839

This species is locally common across the Palaearctic region from Western Europe to the far east of Russia and China, it occurs throughout Asia Minor and North Africa and is present on Madeira and the Azores, it is also widespread in western North America, from Washington to Southern California, where it is thought to have originated from European introductions. In the UK it is generally common across England and Wales though more local and less frequent in the north, it is very local and rare further north to the Scottish Highlands and is widespread in Northern Ireland and Man. Adults occur year round, they are often active through the winter among leaf-litter and under debris etc. and are otherwise active over a long season from early spring, peaking in abundance in late spring and early summer and again in the autumn. The species is widely eurytopic; it often occurs alongside the closely similar and equally common X. linearis (Olivier, 1795) but is more hydrophilic and usually occurs in permanently damp or wet habitats, it often occurs in broadleaf woodland or among low vegetation on heaths and moorland but adults may be frequent in compost, dung and leaf-litter etc and are sometimes common in gardens and other disturbed areas. Both adults are larvae are primarily predatory, hunting for small insects etc among litter or low vegetation, adults are mostly nocturnal and remain among litter and tussocks or under logs etc during the day although they may sometimes be seen running in the open in hot sunny weather. They are frequent in pitfall traps and among extraction samples from a range of habitats and have been recorded from flight-interception traps. Local to Watford in Hertfordshire we found then in large numbers among reed litter in the spring and among compost in domestic gardens.

7.0-9.0 mm. A rather nondescript species; elongate and parallel-sided, head black, pronotum black or dark brown, sometimes with a faint metallic reflection, elytra and scutellum usually dark brown but sometimes entirely black, abdomen black, often lateral and basal margins of the tergites paler, legs pale brown, antennae pale to dark brown, usually with the scape darker. Head elongate, with small and almost flat eyes and long temples which diverge slightly and are evenly rounded to a narrow neck, frontal furrows sinuate and extending to about the centre of the eyes, surface finely and sparsely punctured and with very fine transverse microsculpture, two larger punctures separated by about the distance of each from the corresponding eye. Apical maxillary palpomere long and pointed. Antennae inserted dorsally between the base of the mandibles; scape long and broad, segments 2 and 3 elongate, 4-10 transverse. Pronotum elongate, broadest at rounded anterior angles and narrowed to a more-or-less curved basal margin, disc with two longitudinal series of punctures and sparsely punctured towards the lateral margins, surface generally without microsculpture but there may be very weak microsculpture behind the anterior margin. Elytra elongate and slightly broadened from rounded shoulders to slightly obtuse (from above) posterior angles, randomly punctured and pubescent, the sutural margins overlapping. Abdomen strongly bordered and usually widest behind the middle, all tergites finely punctured and pubescent and with very fine transverse microsculpture. All tibiae with sharp spines externally and paired long apical spurs. Tarsi 5-segmented and simple, claws smooth and without a distinct basal tooth. Easily recognised by the long and curved temples which meet the neck at an obtuse angle, lack of pronotal microsculpture and dark brown or black elytra.