Ampedus sanguinolentus (Schrank, 1776)
This is a very widespread transpalaearctic species occurring throughout Europe except for the most northern parts and extending east through Kazakhstan and Asia Minor to the far east of Russia and Hokkaido; in the south of this range it is generally common from lowland to sub-montane altitudes but in the north is generally rare with populations often occurring in coastal areas and tending to be fragmented by habitat destruction. In the UK it is generally rare (Nationally Notable A) although populations may be large where they do occur; there are thriving populations in Surrey and Hampshire woodlands and scattered isolated records from Sussex, Kent, Somerset and Lincolnshire. The typical habitats are damp lowland and low-mountain deciduous forests, wooded river valleys and acid heath and moorland with suitable host-material; in the UK it is generally a species of ancient deciduous woodland and acid heaths (Joy states ‘chiefly at the roots of heather’). Host plants include various deciduous trees but especially oaks, alders, lime and birch; in the UK it is usually associated with birch but we have recorded it under oak bark in the New Forest. Adults appear from April until late July, early in the season they may be found under bark but they become active during the first warm days and fly to white flowers, especially hawthorn blossom and umbels, and more generally will be found around damp decaying timber; on stumps and trunks, fallen and felled wood, log-piles and exposed roots. Mating occurs in May and June and females oviposit among damp bark or soft decaying xylem where the larvae will develop. Larvae are predatory but, like many other elaterids, probably also consume some decaying plant material, they generally develop over three or four years and pupate in a cell under bark or near the surface of heartwood in late summer, adults are fully developed by the autumn but remain in the pupal cell until the following spring when they become active under bark for a while before dispersing.
This medium sized elaterid is distinguished among the UK fauna by the characteristic bicoloured elytra. 10-12mm. Head, pronotum and scutellum black with fine brown pubescence, elytra red with a variable dark sutural area; this is usually well developed and in extreme cases can extend along the entire length and more than half the width, but is sometimes reduced to a narrow line starting in the anterior third and ending well before the apex but in any case the colour is diagnostic. A continental form, immaculatus Schaufuss, 1882, occurs with almost completely red elytra, and in continental specimens the dorsal pubescence varies from black to yellow, or these colours may vary in a single specimen. Head smoothly convex and finely punctured, antennae serrate, a little more strongly so in the male; the third segment about twice longer than the width across the apex. Pronotum quadrate and widest across the produced posterior angles, laterally sinuate in the basal third then smoothly narrowed to obtuse anterior angles. Surface convex and finely punctured; the punctures are distinct to the lateral margins, especially anteriorly, and not at all confluent, disc without a median furrow, and laterally with a distinct ridge along the produced posterior angles. Scutellum large and more densely punctured than the pronotum; rounded laterally and obtusely angled apically. Elytra parallel-sided for the basal two-thirds then narrowed and smoothly rounded apically, with well-impressed and punctured striae complete to the apex, these are often suffused with black and there is sometimes a wider discrete darer mark towards the base of the second striae, interstices convex, especially towards the base and apex, and finely punctured. Legs entirely dark or, often, with lighter tarsi. Ampedus quercicola (du Buysson, 1887) sometimes has a darkened elytral suture but here the elytral apex is also dark.