Stenus cicindeloides (Schaller, 1783)
This generally common wetland species occurs throughout the entire Palaearctic region from Europe east to China and Japan, it occurs from lowland to low mountain altitudes throughout Europe except for the far north and is widespread in North Africa, including Madeira, and the Near east and has recently been recorded from Iran. It is common throughout England and Wales including the islands, although less so in the West Country, and more local and scattered through Scotland and Ireland. Adults occur in all types of wetland habitats including coastal pools and salt marsh margins, they are generally common on well-vegetated margins of still and running water, especially on reeds, rushes and among dense growths of reed sweet-grass (Glyceria maxima (Hartm,)), often on flood plains and permanently damp grassland, they almost always occur in numbers and often alongside other members of the genus, including the similar S. solutus Erichson, 1840. They are present year-round and active from early spring until late in the year, spending most of their time on the ground or low down on marginal vegetation but during warm weather they climb stems and foliage and are easily spotted. Both adults and larvae are predatory and both are adapted to hunt small insects and springtails etc. in marginal situations, the adults with long legs, large eyes and extendable mouthparts, and the larvae with long legs, palps and mandibles, adults have bilobed tarsal segments and so can move easily on stems and foliage, they can also move very quickly on the water surface by secreting strong detergents from the abdomen. For most of the year they may be sampled by sweeping or pitfall trapping, and during the winter they sometimes appear in samples of reed-litter or stems.
Stenus cicindeloides 1
Stenus cicindeloides 2
Stenus cicindeloides 3
From Tottenham, 1954
5.7mm. Entirely shiny black or with a faint metallic blue reflection, legs and antennae bicoloured black and orange or yellow. Head slightly broader than the pronotum, transverse with large eyes that occupy the entire lateral margin and a short bulging neck, surface strongly and closely punctured and with sparse pale pubescence, antennae yellow, usually darkened from the fifth or sixth segment but always with the apical segments black. Palps entirely yellow. Pronotum quadrate, broadest about the middle and narrowed to distinct angles, the surface strongly punctured and finely pubescent. Elytra transverse and convex, slightly broader than the head, with broad, rounded shoulders and curved apical margins, the surface strongly punctured; a little more strongly and densely than the pronotum, the punctures confluent in places, and finely pubescent. Abdomen long and gradually tapering, often parallel-sided in the basal half, segments without raised borders, pubescent and more finely punctured than the forebody; the punctures becoming finer and denser towards the apex. Femora bicoloured; base yellow and apex black, sometimes substantially so, tibiae yellow with the base at least to some extent darkened. Tarsi substantially pale, the penultimate segment strongly bilobed. Aedeagus sinuate laterally and strongly narrowed in the apical quarter, parameres not expanded apically.