Attelabus nitens (Scopoli, 1763)
This generally common western Palaearctic species occurs throughout Europe and western Russia but probably not through Siberia as is sometimes quoted; there it is replaced by another species, extending south into northern Algeria, Syria and Israel, and north into southern Scandinavia and the UK; here it is locally common throughout England and Wales although generally absent from the West Country. The usual habitat is woodland and parkland where its primary hosts, various species of oak, occur but it has also been recorded from beech, birch and, on the continent, chestnut. Various other hosts e.g. hazel, willow and hornbeam have been quoted in the literature but in the UK it almost always occurs on oak. Adults are active from May to July or later in some years and they usually occur in numbers when found, they take flight or drop to the ground when disturbed but may occasionally be seen basking on foliage in bright sun. Freshly emerged adults feed on young foliage, usually low down and they will attack saplings or coppiced trees when available, they are active during sunny spells but otherwise remain concealed under leaves, following several days of feeding they begin to mate; small groups assemble on leaves and each female will mate repeatedly over a few days, after this the females disperse, sometimes accompanied by a male, to find suitable leaves for egg laying. Fresh leaves low down on the tree are usually chosen and they will invariably be on freshly expanding stems; even in dense populations of beetles where some stems are loaded with leaf-rolls, foliage on previous years stems will generally be ignored. Leaf rolls are formed by the female; a suitable leaf is initially cut transversely through the epidermis and veins using the mandibles and by scraping with the toothed inner margin of the pro-tibiae, it is then left for a few hours to wilt and soften and she will return at night to roll the leaf; it is firstly rolled longitudinally around the main vein axis and then a single egg, or on rare occasions up to five, is laid within the folds, she then continues rolling the leaf from the apex towards the petiole, and then from the outside inwards, forming a tightly folded roll attached to the tree by the partly-severed main vein. Occasionally rolls will be found not to contain a larva and this may
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be due to the female being unable to place an egg correctly, or if the main vein is cut too deeply and the roll falls to the ground during formation. The majority of rolls are made at night when the leaves are more pliable and when finished rolls are typically about 10mm by 7mm, they remain on the tree and turn brown and brittle in the sun over the following few days after completion while the basal part of the leaf remains green and healthy. Rolls begin to fall randomly from the end of May and by late summer the majority have fallen; only rarely do they remain on the tree until leaf-fall. Larval development relies on the moisture content of the rolls and this is maintained by the six to twelve layers of leaf forming the roll, fallen rolls occasionally become mouldy but this does not seem to adversely affect larval development. In very dry seasons females may bite-off recently formed rolls sending them to the ground where they are better able to resist desiccation. Each female will lay up to twenty five eggs in slightly fewer rolls over a period of about ten weeks. Larvae emerge after two or three weeks and begin feeding within the rolls; first instars moult during June or July and the second, and final, instar will feed until September or October and remain in the roll over winter. Pupation occurs within the roll during April, or a little later depending on the season, and adults eclose from late April. Oviposition continues over a long period and larval development is generally rather slow and so during July both instars as well as eggs may be found within rolls.
Adults are unmistakable among the UK fauna, the only superficially similar species being our other member of the subfamily, Apoderus. 4-6mm; females are generally larger than males, and entirely shiny black with the pronotum and elytra bright red. Head with large convex eyes and long temples, the surface coarsely and sparsely punctured, rostrum short and dilated apically, with scrobes visible from above. Antennae black with various basal segments lighter and an elongate and narrow club. Pronotum transverse, evenly rounded and with a strong basal border; without anterior angles or lateral borders, the surface finely and sparsely punctured. Scutellum large, quadrate and coloured and punctured as the head. Elytra transverse, parallel-sided and evenly curved apically, with rows of strong punctures which may become confused towards the base, and with scattered large punctures along the interstices. Legs long and robust; femora clavate and tibiae with small sharp teeth along the inner margins. Male with a single spur at the inner-apical margin of the pro-tibiae, female with two.