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Phloeotribus rhododactylus (Marsham, 1802)







POLYPHAGA Emery, 1886

CURCULIONOIDEA Latreille, 1802

CURCULIONIDAE Latreille, 1802

SCOLYTINAE Latreille, 1804


PHLOEOTRIBUS Latreille, 1797

This widespread Western Palaearctic species occurs throughout Europe from Spain to Greece and north to Sweden and Norway, and across North Africa from Morocco to Turkey and Iran; it has also been recorded from North America and Australia where some of its European hosts have become established. Here it is widespread Across Wales and southern England and there are scattered records further north to the Scottish Highlands. Host plants include various Fabaceae, more especially Cytisus scoparius L, broom, and various species of Ulex L, gorse, although in southern Europe it is also associated with Spartium junceum L, Spanish broom, Calicotome spinose (L.),  thorny broom and C. villosa (Poir.) hairy broom, all widespread Mediterranean species closely related to Ulex and occasionally others e.g. Laburnum sp. Adults occur from March or April until mid-summer and are easily sampled, often in large numbers, by beating dead and weakened shoots and stems over a sheet; their presence may be detected by short trails of white or brown wood dust below exit holes bored out of the stems from pupal cells excavated at the end of larval galleries. Mating occurs in the spring and both sexes bore a short branched tunnel into damaged or weakened stems between 0.5 and 1.0 cm in diameter, the female will then deposit up to forty eggs into each branch and fill it with wood dust etc. Larvae develop through the spring and summer, boring away from the oviposition galleries and through shoots and stems until fully grown in late summer when they pupate in subcortical cells. Adults are active on the surface of stems etc. on warm nights, they disperse by flight nocturnally and at this time may occur far from their host plants e.g. we have recorded them from the cut ends of felled pine trunks in our local woods during April and swept them from Crataegus foliage at the same location during July. When working the host plants over several seasons the numbers of beetles may vary widely from year to year, from great abundance to scarcity, and when beating foliage over a sheet there are sometimes large numbers of various parasitic wasps; in Europe there are 2 widespread species known to specialize in parasitizing Phloeotribus; Spathius brevicaudis Ratzeburg, 1844 and Ecphylus silesiacus (Ratzeburg, 1848), both brachonids.

Phloeotribus rhododactylus

Phloeotribus rhododactylus

© U.Schmidt

Adults are small, 1.4-1.8mm, elongate and cylindrical drab brown to black beetles with a distinctive elytral pubescence consisting of rows of stiff recumbent setae; among the subfamily generally they are unusual in having a pseudolamellate antennal club. Head deflexed and only narrowly visible from above, with entire, i.e. not emarginate, eyes and sparse pale pubescence, antennal scape curved and longer than the 5-segmented funiculus and the club elongate and loosely segmented. Pronotum transverse and lacking lateral margins, broadest across the base and evenly narrowed to a straight anterior margin, posterior angles acute and basal margin widely sinuate, surface coarsely punctured and with sparse pale pubescence. Anterior coxae contiguous, scutellum small and barely visible. Elytra convex, the basal margins raised and granulate and the declivity smoothly curved, with strongly punctured striae and rugose interstices each bearing 1-3 irregular rows of pale setae.  Legs short and robust; pro-tibiae with several sharp teeth externally, and all tibiae strongly widened to a truncate apex. Tarsi 5-segmented with the third segment deeply bilobed. Males are distinguished by a central depression on the frons; in females it is flat.

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