Notiophilus biguttatus (Fabricius, 1779)
This is a widespread and generally abundant native species throughout the Palaearctic region and, following introductions, is now established in the United States., it is common throughout the U.K. north to the Western Scottish Islands and Orkney. In Europe it occurs up to 900m and is a mainly woodland species except in humid areas where it is more eurytopic, here it is to be found in most situations and is usually the Notiophilus seen running on garden or parkland pathways in warm weather. Adults are active from April to September; later in the year they may be found among leaf-litter or under debris etc. where they will pass the winter, at one site in Watford they are common among marginal reed-litter and often appear among large populations of Paranchus albipes (Fabricius, 1796) and Agonum fuliginosum (Panzer, 1809) etc. They are diurnal hunters feeding upon collembola, mites and small larvae etc. and have been observed climbing tree trunks in search of prey, they fly but this is rarely observed. They breed in the spring with larvae developing through the summer and new generation adults appearing from mid-summer although there may be a partial second generation as larvae have been found in late summer. Populations fluctuate widely and there are good and bad years to find adults, a favoured habitat is open arable land where they constitute important predators of aphids etc. and occasionally huge populations build up, in such situations with a little patience they may be seen running between the plants in abundance during warm weather. In general the species is common everywhere and will soon appear by casual searching or in pitfall traps etc. and they occasionally turn up in grass tussock samples during the winter.
4.7-6mm. Upper surface shiny with a strong bronze or sometimes blue reflection. Frons with 6 parallel longitudinal carinae and an oblique ridge beside each eye, the vertex is dull, contrasting with the shiny frons. Pronotum strongly punctured except on the disc, margined and distinctly sinuate anterior to sharp posterior angles. Second elytral interval more than three times wider than the third; the fourth about as wide as third and wider than the fifth (in N. quadripunctatus Dejean, 1826 the fourth is wider than both adjacent intervals near the middle). All interstices shiny, as the wide second interstice; the fourth with a single large puncture before the middle, although there may be an extra one on one side, and another just before the apex. Apically with an ill-defined pale mark that variously extends towards the middle, this soon becomes obvious and is a good field character. The femora and tarsi are metallic black and the tibiae red although darkened to some extent towards the apex.