Rhyzobius litura (Fabricius, 1787)

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POLYPHAGA Emery, 1886

CUCUJOIDEA Latreille, 1802

COCCINELLIDAE Latreille, 1807

COCCIDULINAE Mulsant, 1846

Rhyzobius Stephens, 1829

This Western Palaearctic species is generally common throughout Europe; in the south it extends from Portugal to the Black Sea and is present in North Africa and on most of the Mediterranean and Atlantic islands, to the north it reaches the UK and into southern parts of Sweden and although it occurs in Denmark and Poland it is otherwise generally absent from the Baltic countries, this distribution is probably continuous but there are several countries towards the east e.g. Slovenia, Hungary and Slovakia, where it has not been recorded. In the UK it is abundant throughout England and Wales although it seems to be more coastal in the extreme west, it is very local and mostly coastal in Southern Scotland and Ireland and there are a few scattered records from the northern Scottish Highlands. This is typically a grassland species, it often occurs among low-growing vegetation such as nettle-beds and thistles in open situations and is sometimes attracted to flowering trees and shrubs e.g., it may occur in abundance on flowering gorse, broom and hawthorn, it occasionally occurs on reeds and sedges etc. in wetland situations and on coastal dunes, at the height of the season it is likely to occur in any open and warm situation including parks and domestic gardens and is sometimes abundant on umbel flowers. Adults are present year-round, they overwinter among litter or moss or in low vegetation such as grass tussocks and become active during March, they peak in abundance in May and June and again in August and September and remain active into the autumn, adults will often be caught in flight but the hind wings are dimorphic and so not all are capable of flying. Both adults and larvae predate aphids and other small insects and their early stages but they also consume pollen and possibly fungal spores. Breeding occurs from late April when mating pairs are common on umbels and blossom. Larvae develop from May, they roam openly among foliage and stems as they search for prey and pass through three instars over about four weeks before they are fully-grown. The pale yellow larvae are elongate-oval with flat greyish tubercles  and long clubbed hairs across the body, the last abdominal segment is long and truncate or concave apically and the hind margin of the pronotum has two rows of spines across the middle and the inner margins of the meso- and metathorax have two un-branched spines. Pupation occurs above or below leaves or on stems and this stage lasts between 10 and 12 days, fresh adults appear during July although in some years this may continue into late August. The pupa is superficially similar to the larvae; elongate and pale to bright yellow with long clubbed hairs. Adults can be sampled by sweeping low foliage or flowers in any fairly open situation.

Rhyzobius litura 1

Rhyzobius litura 1

Rhyzobius litura 2

Rhyzobius litura 2

Rhyzobius litura 3

Rhyzobius litura 3

© U.Schmidt

Rhyzobius litura 4

Rhyzobius litura 4

© Lech Borowiec

2.5-3.0 mm. Elongate-oval, convex above and more or less continuous in outline, dorsal surface finely pubescent, colour varies and completely pale specimens are common, typically pale orange with a subapical U-shaped dark mark which may extend beyond the middle of the elytra, and with a dark scutellary mark that is typically triangular but varies in size and shape, appendages and mouthparts entirely pale. Head smoothly convex and finely punctured, with large, coarsely-faceted eyes and long antennae that reach back beyond the pronotal base. Antennae slender with a long three segmented and obliquely-truncate club. Pronotum widely transverse, broadest across acute posterior angles and evenly (varies a bit) narrowed to a straight apical margin, surface finely punctured and very finely microsculptured, evenly convex and without structure. Prosternal process long and triangular, evenly tapering from the prosternal base to a point just before the apical margin – this feature will separate superficially similar specimens of R. chrysomeloides where the process is parallel-sided about the middle and broadly rounded across the apex. The elytral pattern is very variable but the U-shaped subapical mark is typical, and however extensive this becomes it very rarely resembles the double longitudinal marking seen in chrysomeloides, most specimens can therefore be assigned with confidence, elytra otherwise smoothly convex and continuously-rounded.