Crepidodera aurata (Marsham, 1802)
Willow Flea Beetle
This very widespread and generally common species occurs throughout the Palaearctic region from Portugal to China and Japan, it extends south into the Middle East and north west Africa and is common and often abundant from lowlands to mountain altitudes (up to 1500m in Bulgaria) throughout Europe north to the UK and above the Arctic Circle in Fennoscandia and Russia. In the UK it is common and often abundant in England north to Yorkshire and across South Wales but only rarely recorded further north as far as Edinburgh and in north-eastern Ireland. Adults are likely to occur wherever the host trees are present but they are usually common on the margins of rivers, lakes and reservoirs etc., and during the summer they frequently occur on trees in parks and domestic gardens and even on ornamental trees in town centres etc. Host plants include various willows (Salix spp.) and poplars (Populus spp.) but during the summer they may also be found on a wider range of trees including Oak, Alder, Ash and Hazel. Adults occur year-round; they overwinter under bark or debris and among grass tussocks or moss and become active early in the year, usually just before the host leaf buds begin to burst, and their presence is soon obvious by the numerous small and round feeding holes they make in fresh foliage. Mating occurs after a period of maturation feeding and females oviposit in the soil soon afterwards, generally from late April until June, (although they are variously quoted in the literature as ovipositing on the underside of fresh leaves), they deposit eggs singly or in pairs among host roots and larvae develop into the summer. Larvae pass through three instars and probably pupate in an earthen cocoon in the soil and adults emerge over a long season from late June, at this time they disperse by flight and feed on a wide range of foliage but they do not mate and the species is thought to be strictly univoltine. Adults are easily sampled by sweeping host foliage or vegetation around host trees, although they jump powerfully and so can be tricky to tube, they also occur in flight-interception traps throughout the season and in extraction samples of moss and litter through the winter. This is among the most common of the European species; it may occasionally occur in huge numbers and has formerly been a serious pest of osiers grown commercially for basket-weaving etc.
Crepidodera aurata 1
Crepidodera aurata 2
Easily recognized in the field by the brilliant bicoloured appearance, C. nitidula (Linnaeus, 1758) is superficially similar but easily separated with a hand lens, see below. 2.2-3.5 mm. Head and pronotum brilliant metallic blue or green with bronze, copper or violet overtones, elytra blue or green without overtones, legs pale yellow or brown with the hind femora dark brown or black although rarely the legs are entirely dark, antennae pale at the base and gradually darkened to the apices, this is very variable and they may be extensively pale or dark. Head transverse from above, with large convex eyes and narrow, triangular frontal tubercles defined by sharply-impressed grooves. Pronotum transverse, broadest about the middle and narrowed to sharply obtuse posterior angles and small and sharp tubercle which form the anterior angles, surface with randomly distributed large and small punctures and a deep transverse impression between small longitudinal basal fovea. Elytra broadest behind the middle, with rounded shoulders and a continuously-curved apical margin, with complete and strongly-punctured striae and very finely punctured interstices. Hind femora greatly enlarged, tibiae narrow, slightly sinuate and without obvious apical spurs, all tarsi pseudotetramerous, male front tarsi not modified. Claws smooth and without a basal tooth.
Generally larger (3.0-4.1mm)
Elytral striae not regular, usually sinuate and fading in the apical third
Elytral interstices with larger punctures, these often run in longitudinal series so that in places they resemble striae