Acalyptus carpini (Fabricius, 1792)
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POLYPHAGA Emery, 1886
CURCULIONOIDEA Latreille, 1802
CURCULIONINAE Latreille, 1802
ACALYPTINI Thomson, C.G., 1859
ACALYPTUS Schönherr, 1833
This locally common Palaearctic species occurs from lowland to alpine latitudes throughout Europe north to the UK and far beyond the Arctic Circle in Fennoscandia, extending east to China, Korea and Japan, and following introductions is now established and widespread in North America. Here it is locally common in East Anglia but otherwise scattered and very local in central southern England and South Wales. Adults are present year-round, they are active over a long season from March until October and the new-generation appears in July and August but they remain subterranean pupal cells until the following spring. Host plants include various species of Salix L. (willows), in Europe S. caprea L. (goat willow), S. cinerea L. (grey willow), S. purpurea L. (purple willow or purple osier), S. alba L. (white willow), S. eleagnos Scop. (olive willow), S. viminalis L. (common osier) and S. fragilis L. (crack willow) as well as various hybrids and cultivars, and typical habitats include those where these host are abundant; wetlands, carr, damp woodland and parkland etc. Mating occurs early in the season and eggs are laid in female catkins, larvae feed within the catkin stem, they develop rapidly and are full-grown by late May or June when they drop to the ground and pupate in subterranean cells, new-generation adults appear from the second half of July but remain in their cells until the following spring. Adults may be sampled by beating catkins in the spring and foliage through the summer; they usually occur in small numbers and rarely more than a few on any single tree.
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1.8-2.6mm (male), 2.3-2.7mm (female). Elongate oval with a small head, transverse pronotum and elongate elytra which are much broader across the base than the base of the pronotum. Body reddish brown to black and usually obvious beneath the scales, appendages pale red, often with the femora darker. Head with short divergent temples behind symmetrical and weakly convex eyes, interocular distance slightly narrower than the base of the rostrum. Surface with dense forwardly-directed narrow pale setae. Female rostrum almost as long as the head and rostrum combined, male rostrum a
little longer than the pronotum. Antennae inserted about the middle of the rostrum, funiculus 7-segmented but may appear 6-segmented as the eighth segment is transverse and forms the base of the club. Pronotum widest about the base and subparallel or weakly narrowed in the basal third, then strongly narrowed to a weak subapical constriction and weakly curved anterior margin. Surface with shallow punctures visible under pale elongate scales that are directed obliquely forward. Scutellum small, triangular and densely clothed with setae. Elytra about 1.3X longer than wide, widest about the middle and weakly rounded laterally, with complete punctured striae between wide and flat interstices, with moderately dense recumbent scale-like setae which are often denser on the first interstice. Femora and tibiae unarmed, tibiae unmodified apically. Tarsi pseudotetramerous with the terminal segment longest. Claws well-separated at the base, smooth and without a basal tooth.
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A second European species, A. sericeus Gyllenhal, 1836, is also widespread and locally common on the same hosts but does not occur in the UK, it differs from the present species in having the antennal club and often the distal part of the funiculus black and very dense fine scale-like dorsal setae which in places obscure the elytral striae.