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Xylocleptes bispinus (Duftschmid, 1825)







POLYPHAGA Emery, 1886

CURCULIONOIDEA Latreille, 1802

CURCULIONIDAE Latreille, 1802

SCOLYTINAE Latreille, 1804

DRYOCOETINI Lindemann, 1876

Xylocleptes Ferrari, 1867

This western Palaearctic species is widespread and locally common in central and south-eastern Europe, it is otherwise generally scarce, extending north into the UK and the Baltic countries where it reaches the southern-most provinces of Sweden. To the south it is known from Spain, Algeria and Asia Minor, including Crimea. In the UK it is locally common across southern and central England north to the Humber and also known from parts of Wales. The species is associated with Traveller’s Joy (Clematis vitalba L.), in Europe possibly also with ornamental members of the genus such as C. orientalis L, and it has sometimes been said to be associated with Grape vines (Vitis L.) In all probability the species is largely monophagous on C. vitalba, but the species was considered as a biocontrol agent to help control Traveller’s Joy, which is a prolific and invasive plant that became naturalized during the 1920s, but experiments suggested that it might also attack various native species and so it has not been used. Adult beetles are present year-round; they overwinter in host stems and are active from April until September or October, peaking in abundance during April and May. Mature beetles emerge from stems in the spring and fly during the evening to find new host material, the males signalling with pheromones to attract females to suitable sites. Males then excavate a mating chamber near to a node, and both sexes enter and mate. Mated females then make several small cavities near to the mating chamber and insert about 20 eggs into each; she will then mine a spiral gallery at the end of the mating chamber, often cutting off water and nutrients to the rest of the plant. The eggs are laid close together and covered with wood dust. Larvae develop over about 50 days and pass through 3 instars, they initially move along the spiral tunnels produced by the female, and then begin feeding on living tissue beneath the bark. When fully grown the larva will seal off the feeding gallery and excavate a pupal chamber in the centre of the stem. Development from egg to adults takes about 60 days, and the new adults may feed and disperse, although it is thought that most will remain in situ, but they will mot mate until the following spring. Exit holes are easily spotted during the winter, and these stems should be broken over a sheet in order to find adults among the debris, at other times adults may be found in stems, swept from host foliage or sampled with flight-interception traps. They will almost always occur in numbers, and among these, especially from heavily-infested stems, there may be specimens of the laemophloeid, Leptophloeus clematidis, which is believed to predate the present species.

Xylocleptes bispinus

Xylocleptes bispinus

2.1-3.2 mm (males), 1.8-3.2 mm (females) Elongate and cylindrical, entirely pale to dark shiny brown or with the forebody darker than the elytra, body with sparse and mostly erect pale pubescence. Head almost concealed from above by the apical pronotal margin, evenly convex, finely punctured and with dense long pubescence, eyes widely transverse and strongly emarginate anteriorly, temples long and almost smooth. Antennal scape long and evenly broadened from the base, second segment large and globose, segments 3-6 transverse, and segments 7-9 form a round and fused club where the apical margins of the segments are visible as arcs of tiny hairs. Pronotum elongate, broadest about the middle and narrowed to rounded (from above)angles, evenly convex; in lateral view almost flat towards the base and gently curved towards the apex, granular in the apical half (granules often partly arranged in concentric arcs) and simply punctured in the basal half, often more sparsely so on the disc. In males the pronotal cuticle is mostly smooth and shiny, whereas in females it tends to be microsculptured and dull. Scutellum triangular, tiny and hardly visible. Elytra elongate and near parallel-sided from rounded shoulders to separately-rounded apical margins, surface for the most part randomly punctured, but these may form regular rows in places, the elytral apex is strongly sexually dimorphic. In males the declivity is well demarked from the surface, concave either side of the suture, and has a single strong lateral spine. In females it is less strongly demarked from the surface, weakly convex and with fine lateral tubercles. All tibiae with an external series of prominent teeth towards the apex. All tarsi with 5 simple segments, the terminal segment long and curved. Claws smooth, and with a tiny basal tooth. Most scolytids present challenges, but identification here is straightforward if specimens are associated with the host plant.

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