Gyrinus suffriani Scriba, 1855

This widespread though generally rare species occurs through most of Europe from the Pyrenees to the UK and southern Fennoscandia and extends sporadically across the Mediterranean countries as far as the Caucasus, Turkey, Syria and southern parts of European Russia. Here it is a very local and rare lowland species confined mostly to the south-east below London and East Anglia, it was formerly recorded from south west Scotland but now seems to be extinct there, it has also vanished from some of its former southern localities and beyond the south east there are modern records only from South Wales and Anglesey. Adults overwinter and are active over a long season from March until November, they usually occur in small numbers and seem to prefer well-vegetated marginal areas of still and slow-moving water, sometimes open areas of flooded reed bed margins or drainage ditches, and are notably fast moving on the surface although they probably spend much of their time submerged. Adults mate early in the year and oviposition has been observed in late spring, the predaceous larvae develop among aquatic vegetation but leave the water to pupate in a cell constructed of plant debris etc, adults eclose within a week or two and the entire cycle from egg to adult has been observed to last eight weeks under artificial conditions.

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4.0-6.2mm. broadly elongate-oval and widest about the middle, dorsal surface shiny black, often with a bronze lustre towards the lateral margins, ventral surface extensively black (rarely reddish), usually with the elytral epipleura red and the hypomera, mesosternum and gonocoxosternites brownish. Scutellum flat, without a small median ridge at the base, pronotum and elytra smooth, without or with at most a very weak and indistinct microsculpture. Elytral striae composed of rows of punctures that attenuate towards the apex; the outer rows a little stronger, the width of the tenth interstice about twice that of the punctures in the tenth stria, punctures in the transverse subapical series much weaker than those of the striae on the disc and sometimes obsolete. Tarsal claws yellow.