Erotides cosnardi (Chevrolat, 1829)

This is a widespread though very local and generally rare species throughout western and central Europe extending north into southern Scandinavia and east into western Siberia, the typical habitat is long-established mixed or deciduous woodland where the beetles develop in decaying wood of a range of deciduous trees e.g. birch, beech and ash. Adults are short-lived and appear from April to June depending on latitude, they are diurnal, occasionally swarming around host material and have been observed at flowers and birch sap and in flight in the evening. Here it is a very rare and local species with about 10 confirmed records from several sites in West Sussex and the Wye Valley in Herefordshire and Gloucestershire. Adults have been found by sweeping vegetation around host material or have been observed on nearby grass stems, they are active during hot weather and all records have been from May and June. In the UK larvae are thought to develop among decaying white heartwood in old beech trunks in vegetated open woodland, parkland or wooded pasture etc.

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Adults are readily recognized by the overall brown colouration with the pronotal disc to varying extents darker. 7-8mm, elongate and parallel-sided with a triangular head usually only narrowly visible from above. Head convex either side of a median depression, finely punctured and rather densely pubescent and with large convex eyes. Antennae inserted under the lateral margins, long and robust with the second segment much shorter than the others, 3-11 elongate and at most only weakly serrate. Pronotum with a central cell open to the anterior margin and five unequal lateral cells, the posterior open to the basal margin; anterior margin a little narrower than the basal margin and lateral margins sinuate in the basal half. Scutellum quadrate and roundly lobed apically; dark, as the pronotal disc, and finely punctured and pubescent. Elytra with rounded and sloping shoulders and variously narrowed about the middle, each with four prominent longitudinal costae separated by two uneven rows of cells. Legs long and robust, entirely dark or with the tarsi variously lighter, femora broad and parallel-sided, tibiae curved and thickened towards the apex. Tarsi 5-segmented, with segments 3 and 4 bilobed.