Dorytomus ictor (Herbst, 1795)
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POLYPHAGA Emery, 1886
CURCULIONOIDEA Latreille, 1802
CURCULIONINAE Latreille, 1802
ELLESCINI Thomson, C.G., 1859
DORYTOMINA Bedel, 1886
DORYTOMUS Germar, 1817
In Europe this is a mostly southern and central species that extends sporadically north to southern Fennoscandia and the UK while the wider distribution includes most of the Palaearctic region; through Siberia and east to Japan. In the UK it is a very local species of southeast and central England and south Wales with only very few records north of the Wash and none further west than West Sussex. Adults overwinter, sometimes gregariously, and are active very early in the year, from January although they will often be active during mild winter spells, and they persist into April or May. Mating occurs early in the season when pairs may be found on trunks or nearby fences etc. but they are nocturnal and so possibly under-recorded at this time, during the day they remain among bark or in wood crevices and are inactive. At night they often occur in numbers and sometimes alongside other Dorytomus species; locally we are fortunate in having a site near Watford town centre where several species congregate on metal fence railings in large numbers early in the year. Host plants include various poplars, in the UK Populus nigra L. (Black Poplar) and its hybrids but a wider range of species have been recorded on the continent including P. tremula L. (Aspen), P. balsamifera Mnch (Balsam Poplar) and P. Canadensis var. serotina (Hartig). Females gnaw holes into unopened flower buds and oviposit within, sealing the holes with a yellow secretion, and larvae feed among the catkins. Larval development is rapid and they are fully-grown within about three weeks, pupation occurs within the catkin or nearby and new generation adults appear during April or May. Adults may be found through the season by sweeping suitable foliage or by nocturnal searching but they generally spend the day among bark and may be difficult to find. Typical habitats include wetland margins, parks and commons where the hosts are present; locally they occur mostly on large mature trees even though there are abundant saplings nearby.
Dorytomus species can be notoriously difficult to identify but the present species should be straightforward; the pronotal and elytral setae combined with the short rostrum are distinctive. 3.8-4.5mm. Overall dark brown or grey with patchy lighter pubescence to the pronotum and elytra. Head with recumbent pale pubescence and large, weakly convex eyes that follow the outline, Rostrum short and broad, shorter than the head and pronotal length combined, and densely scaled at the base. Pronotum broadest in front of the middle then more or less straight to the posterior angles, strongly and densely punctured and with patches of light and dark pubescence, anterior lateral margins with long recumbent setae that overlap the side of the head. Anterior prosternal margin gently curved but not emarginate or channelled medially. Elytra vaguely patterned with light and dark scales, more dense laterally, the more shiny striae usually obvious on the disc, and without erect or semi-erect setae; in dorsal view only the scales are visible along the lateral margins. Most specimens have extensive areas of pale scales towards the lateral margins of the prothorax and elytra and typically the sutural, sixth and seventh interstices are largely pale. Femora strongly toothed, a feature that will distinguish this species from various Erirhinini with which they are sometimes confused. The female rostrum is a little longer and shinier and the front femora less strongly toothed compared with the male.