Andrion (=Sitona) regensteinense (Herbst, 1797)
Occurs throughout mainland UK with modern records north to Easter Ross (NBN), this species is common and usually abundant although localised by its host plants; Ulex europeus (Common Gorse) and probably other Ulex species, Cytisus scoparius (Broom) and probably Genista spp. (Morris, 1997). Both Gorse and Broom occur throughout our area in parks, on wasteland and grass verges and as ornaments in gardens, amenity planting and around industrial estates but so far (Dec 2008), and despite much sampling, we have recorded regensteinensis only from Common moor, and here they are abundant. Both Gorse and broom are common on the higher dry parts of the moor and there are old and woody examples of each. Also on the moor, although not too commonly, is Genista anglica (Petty Whin) which we have repeatedly sampled for the beetle but without success. We have recorded regensteinensis from all months of the year; during the winter they are active in mild spells and may readily swept, from March or April, depending on season, they become active and abundant and remain so through the summer and Autumn.

Larvae feed within root nodules upon cells containing nitrifying bacteria (Danthanarayana, 1967) and new generation adults, from eggs laid in the spring, appear in late summer and autumn.
Although there are several similar species occuring on these plants eg Charagmus(=Sitona) griseus (Fab.) or Sitona striatellus Gyll., the slender, long legged and distinctly arched form of regensteinensis will soon become familiar.

3-6mm (Morris,1997) Upper surface with recumbent metallic scales, colour varies from brilliant bronze to dull green, generally with distinctly contrasting longitudinal rows; along centre of pronotum, elytral suture and from elytral humeri. Underlying cuticle black. Head coarsely and closely punctured, eyes convex and prominent, temples widened towards base. Rostrum quadrate to slightly transverse, scrobes bent down in front of eyes and narrowly visible from above, with a deep central furrow from antennal insertions to hind margin of eyes. Antennal insertions hidden. Scape somewhat abruptly thickened towards apex and much shorter than distance across eyes, red or brown, remainder of antennae dark. Funiculus 7 segmented, segments 1 and 2 elongate, remainder quadrate, club elongate and pointed. Pronotum slightly transverse, without borders, coarsely and closely punctured and with scales a little larger than those on head and elytra. Broadest behind middle and constricted at base, in side view the separate convexities of the pronotum and elytra at their junction is characteristic. Scutellum, of which only the apex is usually visible, with recumbent scales only. Proportions of the elytra vary; in our specimens from (L:W) 1.38-1.71 but in most specimens the overall impression is of an elongate insect, scales recumbent and mostly elongate oval, striae very strongly punctate, interstices flat or very weakly convex and very finely punctured, often barely visible at X20. Each interstice with a row of prominent, backwardly curved, raised setae, colour varies from white to dark grey. Femora black, clavate and variously scaled. Tibiae and tarsi lighter, very variable. Claws well developed, especially the anterior pair, and free. Male protibiae strongle bent inwards towards apex and with proment apical teeth. In most specimens the mid and, more especially, fore legs are disproportionately long so giving the beetle and awkward gangly appearance

Description taken from 12 Watford specimens X20

Danthanarayana,W 1967. Host specificity of Sitona beetles. Nature 213:1153-1154