Olibrus corticalis (Panzer, 1796)
POLYPHAGA Emery, 1886
CUCUJOIDEA Latreille, 1802
OLIBRUS Erichson, 1845
This widespread European species occurs from Portugal to Asia Minor, north tom Scandinavia and south to the northern Mediterranean coasts. In the U.K. it is common in southern England north to the Humber although records are more scattered and local in the west. Adults occur from March to August and are likely to be found wherever the host plants are growing, typically grass verges, wasteland and disturbed ground generally. During warm weather they may be seen in a range of flowers but preferred hosts include various composits e.g. groundsel (Senecio vulgaris L.), ragwort (S. sylvaticus L.) and sticky ragwort (S. viscosus L.). We have also found them frequently on dandelion (Taraxacum), coltsfoot (Tussilago) and common cat’s ear (Hypocharis). They may need careful looking for as in anything but warm and bright conditions they tend to remain low down and inconspicuous among the florets. They also turn up by general sweeping on grassland and among low vegetation; in hot conditions often in numbers. Females oviposit in flower-heads where the larvae will develop consuming liquids, adults feed on pollen. They fly well and often occur at u.v. light; in our local town centre garden they have occurred at light each month from March to September with large numbers in July and August.
Most specimens are distinctively coloured and so the species soon becomes obvious in the field; head and pronotum dark brown, the head generally a little darker, elytra pale with the suture, lateral margins and a triangular mark at the base dark. In var. assimilis Flach, 1889 the entire surface is dark. All appendages pale. 2.5-2.9mm. The form is elongate-oval and moderately convex and the entire upper surface is shiny and very finely punctured and microsculptured, this is most obvious at the base of the head and pronotum at X100. The head is transverse and convex with the eyes forming a lateral angle; the temples are long and narrowed towards the base but are generally hidden by the thorax. The antennae are inserted under the anterior margin of the head in front of the eyes, the terminal segment is characteristic of the genus being constricted in the apical third. Pronotum often pale laterally, the base and sides finely bordered, the front angles weakly produced and perpendicular, the hind angles a little obtuse. The elytra bear longitudinal lines of fine punctures, between which the surface is randomly and very finely punctured (X60). Each with 2 well-impressed striae from near the apex to at least the basal third, the sutural stria usually continued to the apical angle and both converging just before. Legs, including the claws, pale. Tarsi 5-5-5, segments 2 and 3 at least to some extent bilobed, segment 4 tiny and often not visible among the lobes of the fourth. Claws smooth and toothed at the base.
Olibrus corticalis 1
© Lech Borowiec http://www.cassidae.uni.wroc.pl/Colpolon/index.htm
Olibrus corticalis larva