Rhyzobius chrysomeloides (Herbst, 1792)
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POLYPHAGA Emery, 1886
CUCUJOIDEA Latreille, 1802
COCCIDULINAE Mulsant, 1846
Rhyzobius Stephens, 1829
Widespread and locally common across Europe from Portugal to Ukraine and north to the UK, Denmark and Southern Sweden, this very distinctive ladybird seems to have increased in range and abundance over recent decades. There are also records from Northwest Africa, Madeira and Asia Minor, which might suggest a further southern expansion of the range. The species was first recorded in the UK from Surry in 1996 and it now occurs commonly throughout much of Southern England. Adults are present year-round, they overwinter under bark or among ivy or litter etc. and are often active in all but the coldest spells. They are associated with a wide range of trees and shrubs in almost any situation but are often common in disturbed habitats such as domestic gardens and parks. Many publications quote the species as favouring various conifers, and they can be common on pines, junipers, firs and larch, but from experience they are just as common on both evergreen and deciduous trees and shrubs. Beating trees and shrubs may produce adults at any time, during the winter they are often common on ivy and may be found on Yew and Holly etc., and at other times they tend to occur in the beating tray in most situations. Adults become active in the spring and may be found in numbers on Hawthorn and other blossom, with mating pairs often present, and later on among foliage and a range of flowers, and in domestic situations they sometimes appear in numbers on garden refuse bins. The bionomics have not been studied in the UK but both adults and larvae are general aphid predators, and while mating pairs may be found over a long spring and summer period, the species is thought to be exclusively univoltine. Later instar larvae are pale grey to greyish-brown with a darker head and legs and dark maculae to the thoracic and abdominal segments, these form four longitudinal series along the dorsal surface. Each abdominal segment has a pair of tubercles towards each lateral margin which bear several long pale setae. Pupation occurs on bark or on the surface of leaves.
2.5-3.5mm. Elongate-oval and discontinuous in outline, finely pubescent and entirely pale brown but for various darker elytral markings. Head with large and coarsely-facetted eyes and long (reaching back to the pronotal base), weakly-clubbed antennae. Pronotum transverse and broadest near the base, lateral margin variable but usually almost straight in the basal half then strongly-curved to rounded anterior angles, lateral and basal margins finely bordered, basal margin strongly sinuate and entire surface moderately strongly punctured. Elytra evenly curved from slightly-angled shoulders to a continuous apical margin, surface very finely microsculptured (X25) and randomly punctured throughout, more strongly so than the pronotum. Dark elytral pattern varies but usually consists of double parallel lines obliquely joined at the base and connected across the apex to the suture. The normal elytral pattern is very distinctive and soon becomes familiar, especially in the field, but more extensively darker (in which the pronotum may also be darkened) or paler specimens occur which may cause confusion with the very common R. litura (Fabricius, 1787). Compared with litura the present species is less convex and a little more elongate, the pronotum is less strongly narrowed from the base, and the prosternal keels are distinct; converging from the base then parallel-sided before a rounded apex.