Crepidodera aurata (Marsham, 1802)
Widely distributed below a line from north Wales to Middlesborough, further north there are a few records from Cumbria, Dumfries and Galloway and Glasgow (NBN). By far the most common species of crepidodera locally, aurata is abundant throughout our Watford area on willows in just about any situation. Sweeping the foliage during warm weather will usually produce them, often in numbers, and their presence may be detected by small, round feeding holes. Species quoted as host include Salix alba, S.triandra, S.fragilis, S.caprea and S.viminalis (Konstantinov, 1996). They also occur, although much less frequently so, on Aspen (Populus tremula), Black Poplar (P.canadensis), Hazel (Corylus), Blackthorn (Prunus spinosa), Field maple (Acer campestre), Oak (Quercus), Ash (Fraxinus) (Cox) and we regularly find them on the large stand of Adler (Alnus) at Cassiobridge. There is a single generation and adults occur throughout the year, hibernating under bark or among debris etc around logs. They become active early in the spring and may be swept from trees around the time the leaf buds begin to open. Larvae have been reared on osier roots (Steinhausen, 1996) and pupation probably occurs within an earthen cell (Cox, 2008).

2.3-3.3mm. Upper surface brilliant metallic and bicoloured; head and pronotum blue or green with strong bronze, copper or violet overtones, elytra unicolorous blue or green without overtones. Basal segments of antennae testaceous, usually gradually (never abruptly cf C.plutus) darkened from fifth segment but this varies as we have specimens with almost entirely dark antennae. Longitudinal ridge between antennal insertion well developed with two oblique furrows from its base to the eyes, vertex behind these smooth and shiny or very finely punctate. Coarsely punctured beside large and prominent eyes. Pronotum bordered laterally and basally, front and hind angles denticulate. Convex, surface with a mix of large and small puntures. With a deep transverse impression parallel to base and, either end of this, a small longitudinal impression extending to hind margin. Lateral margins of elytra weakly sinuate and finely bordered to apex, entirely smooth ie without a tooth near the sutural angle (a diagnostic feature for C.nitidula). Larger punctures on elytra arranged in distinct rows, as striae. Interstices very finely punctured, flat and shiny or very finely and obscurely rugose, especially behind middle, just visible at X20. Hind femora dilated, in mature specimens black but always darker than tibiae. Legs otherwise testacious. Male protarsi not modified.

Aedeagus characteristic; weakly constricted longitudinally and rounded at apex. Spermatheca characteristic; as drawn our figure is a little different from that given by Konstantinov but in all our watford specimens the structure is as figured.

Description from 11 Watford specimens at X20

Konstantinov, A.S. 1996 Review of palearctic species of Crepidodera. Spixiana 19/1:21-37.
Steinhausen, W. 1996 Biological remarks on rearing and collecting of middle European leaf beetle larvae. Chrysomelid biology 3, General studies Amsterdam: SPB Academic Publishing:93-105.

see ID Aids for a key to the genus.