Cionus scrophulariae (Linnaeus, 1758)
POLYPHAGA Emery, 1886
CURCULIONOIDEA Latreille, 1802
CURCULIONINAE Latreille, 1802
CIONINI Schönherr, 1825
CIONUS Clairville, 1798
This native Palaearctic weevil occurs commonly throughout Europe except for the far north, North Africa, Asia Minor and extends east into Siberia, and following recent introductions it has become established in north-eastern America and is spreading. Here it is common throughout most of England and Wales although generally missing from the northeast and there are sporadic records from Scotland north to the Highlands. Adults occur from April until late in the autumn and typical habitats include roadsides, parks, woodland borders and marginal situations, often where they are shaded and usually where the host plants are common. Hosts include various species of Scrophularia L., especially S. nodosa L. (Common Figwort) and S. auriculata L. (Water Figwort) but also S. scorodonia L. (Balm-leaved Figwort), Verbascum thapsus L. (Common Mullein), V. lychnitis L. (White Mullein), V. phlomoides L. (Orange Mullein) and Limosella aquatica L. (Water Mudwort) and adults have been observed feeding on a range of introduced plants including Phygelius capensis E.May (Cape Figwort) and Buddleja spp. Adults may be found early in the season on host foliage, they feed on tender foliage for a while before mating occurs in April and May, when disturbed they fall to the ground and remain still, resembling a particle of soil and can be very difficult to find. Eggs are laid among or within the flower buds and larvae consume the developing seed pods, flowers, flower buds and terminal foliage, they mostly feed on the underside of leaves and can be very active, they are dark coloured, almost black, and covered in a shiny and sticky secretion which makes them distasteful to predators and is thought to give some protection from parasites. They have been recorded from May to September and they often occur in numbers; their presence may be detected later in the season by the extensively perforated leaves and damaged areas of terminal shoots. Pupation occurs from July on the underside of leaves or among flowerheads and the pupa resembles an unopened flower bud. Adults may be swept from host plants through the season but in the spring they disperse and may occur among grass or on shrubs far from any obvious host material.
Species of Cionus Clairville, 1798 are very distinctive among our fauna and should not be confused with any other genus, the present species may be distinguished by the extensive pale scales to the pronotum and the dark grey and black scales which cover alternate elytral interstices. 3.5-5.0mm. Head mostly concealed within the thorax so that the convex eyes appear to occupy the entire margin, vertex narrow; black with elongate pale scales, rostrum long and slightly expanded apically, in the male about as long as the head and pronotum combined, in the female longer. Antennae slender, the scape gradually and only weakly expanded towards the apex, the funicular segments weakly elongate to quadrate and the club long and narrow. Pronotum broadest across the base and strongly narrowed to straight anterior margin, entirely covered with dense pale scales. Elytra elongate with broad rounded shoulders and strongly narrowed in the apical quarter, colouration distinctive; with a large round black mark in front of the middle and another before the apex, each bordered internally with a patch of creamy or yellow scales, sutural and odd-numbered interstices with alternating areas of creamy and black scales, even-numbered interstices clothed with contrasting paler grey scales. In lateral view the tessellated interstices usually appear more convex and raised slightly above the others. Legs long and robust, femora and tibiae patterned with pale and dark scales, front femora weakly toothed, middle and hind femora strongly so.