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Sitona suturalis Stephens, 1831







POLYPHAGA Emery, 1886

CURCULIONOIDEA Latreille, 1802

CURCULIONIDAE Latreille, 1802

ENTIMINAE Schönherr, 1823

SITONINI Gistel, 1848

Sitona Germar, 1817 

Widespread and generally common throughout most of the Palaearctic region to the far east of Russia and Japan; in Europe it occurs from the Pyrenees north to the Arctic Circle in Scandinavia and south to Greece and Asia Minor, including many of the islands, but it is absent from North Africa. In the UK it is generally common throughout southern and central England and Wales, though less so in the West Country, and much more local and scarce further north into southern Scotland with occasional records from the Highlands and the Western Isles, it is present on Anglesey though absent from Man, and very rarely recorded from Northern Ireland. Adults occur year-round; they overwinter among litter or in tussocks etc. and are active from March until late in the autumn, peaking in abundance from May until July. Adults are brachypterous and mostly diurnal, they occur in most fairly open habitats; woodland and arable margins, waste ground, grassland, road verges, coastal dunes and even salt marsh margins, and they usually occur in numbers. The usual hosts are Meadow Vetchling (Lathyrus pratensis L.) and various vetches (Vicia L.); in the UK especially Bush Vetch (V. sepium L.) but more generally also Tufted Vetch (V. cracca L.) and Fodder vetch (V. villosa Roth.), and it is sometimes quoted from restharrows (Ononis L.) Mating occurs in the spring following a period of feeding on host foliage and females oviposit in the soil near to host roots. Larvae develop through spring and summer in the soil, feeding ectophagously on roots and root nodules, and pupation occurs during the summer in an earthen cell. The new generation appears during late summer and early autumn and these may feed but will not mate before overwintering. The species seems to be univoltine throughout the range. Adults may be swept or beaten from suitable foliage in most situations, and while they may occasionally occur in very large numbers, especially among fodder crops etc, they are not classed as a serious pest.

Sitona suturalis 1

Sitona suturalis 1

Sitona suturalis 2

Sitona suturalis 2

3.3-4.5 mm. A robust looking species with a large head and pronotum and parallel-sided elytra, dorsal surface with adpressed metallic scales which are usually extensive on the head and form stripes on the pronotum and elytra, and very fine pubescence but without erect setae towards the elytral apex. Head strongly and in part rugosely punctured and more or less flat between large and weakly convex eyes, median impression usually broad, deep and reaching back onto the vertex (at least to the posterior margin of the eyes), and rostrum not keeled laterally. Antennae reddish or darkened towards the apex, sometimes with the scape red and the funiculus and club contrastingly dark. Pronotum slightly transverse, broadest at or a little in front of the middle and narrowed to obtuse angles, surface evenly convex and moderately strongly punctured throughout, pale metallic scales usually dense laterally and along the middle, sometimes also forming partial transverse bands in front of and behind the disc. Front coxae inserted towards the front of the prosternum, reaching or almost reaching the subapical constriction. Scutellum evenly and densely scaled throughout, the scales similar to those on the odd-numbered elytral interstices.  Elytra elongate and broad; 1.5-1.6X longer than wide, and hardly broadened from rounded shoulders to a smoothly continuous apical margin, striae strongly punctured throughout, interstices rugose towards the base, otherwise smooth and flat, second and third interstices parallel throughout. Elytral scales tend to get rubbed in life but in fresh specimens the even-numbered interstices have small brownish scales and the odd-numbered interstices have larger metallic coppery, greenish or golden scales, in most specimens longitudinal stripes are discernible on the first, third and fifth interstices. Legs usually bicoloured with dark femora, red tibiae and red or darkened tarsi. In males the front tibiae are more strongly curved towards the apex and all tibiae have a sharp tooth on the internal apical margin, in females the front tibiae are less strongly curved before the apex and all tibiae lack the apical tooth.

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