Bembidion lampros (Herbst, 1784)
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ADEPHAGA Clairville, 1806
BEMBIDIINI Stephens, 1827
Metallina Motschulsky, 1850
This is among the most common of the European carabids, it occurs throughout the entire Palaearctic region and is now established in eastern North America, having been accidentally introduced with ships’ ballast, it occurs throughout Europe from lowlands to above the tree line in mountain areas and north beyond the Arctic Circle in Scandinavia, it extends south to North Africa, the Near East and many of the Mediterranean islands but is absent from the Atlantic islands. Here it is generally abundant throughout England, Wales and southern Scotland and more local and scarce to the far north of Scotland and across Ireland, it is also present on all the islands except for the Outer Hebrides, Orkney and Shetland. Adults are present year-round, they are active from early spring and peak in abundance during July and August, they occur mostly in open, dry habitats exposed to the sun; parkland and gardens etc. but especially on grazed grassland, hillsides and arable land, they remain active into the autumn and then move to overwintering quarters among litter and tussocks etc. on headlands, wooded borders or along hedgerows. Adults are wing dimorphic and are known to disperse by flight and so they tend to occur in just about any open situation during the summer, they are diurnal and active on the surface, running and exploring cracks and debris, they often occur in large numbers over a wide area and because of the bright metallic colouration can hardly be missed. Breeding begins early in the year and continues through the spring, larvae develop through the spring and summer and new-generation adults appear from July or August, these will overwinter and survive into the next summer but it is not known whether they breed for a second time. Both adults and larvae are predatory and adults will also feed on dead insects and other small animals, they hunt on the ground and in the summer are thought to be among the main predators of crop pests such as cabbage root fly and various aphids. Adults are easily sampled by pitfall trapping but they are easily observed as they are very active in warm weather.
3-4mm. Body metallic bronze or more rarely bluish or greenish, legs pale brown or with the femora darkened and metallic, antennae dark with the base of the first three segments pale. Head smooth and mostly unpunctured, with large convex eyes that make up most of the lateral margin, each eye with two adjacent setiferous punctures, frontal furrows single posteriorly and dilated medially ; the outer margin curved between the anterior setiferous puncture and the clypeus. Pronotum cordate; broadest in front of the middle and strongly constricted and sinuate to protruding posterior angles, the surface with a median longitudinal impression and variously depressed, wrinkled and punctured in front of the basal margin. Elytra with six strongly punctured striae which fade beyond the middle and usually with a partly developed seventh stria consisting of up to eight small punctures, interstices at most only weakly convex, the third usually with two setiferous punctures, basal margin angled and reflexed behind the shoulders and not reaching the scutellum.
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Easily recognized among our Bembidion by the cordate pronotum, angled basal margin of the elytra and substantially pale legs, only B. properans (Stephens, 1828) might cause confusion but here the seventh elytral stria is almost as strongly developed at the base as the sixth and includes at least nine punctures, and the frontal furrows are parallel-sided in front of the anterior setiferous puncture. In series the lateral pronotal margins of properans will be seen to be more widely explanate. Basal pro-tarsal segments of the male broader than those of the female.