Subcoccinella vigintiquattuorpunctata (Linnaeus, 1758)

24-spot Ladybird

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POLYPHAGA Emery, 1886

CUCUJOIDEA Latreille, 1802

COCCINELLIDAE Latreille, 1807

EPILACHNINAE Mulsant, 1846

Suboccinella Guérin-Méneville, 1844

The only member of the genus and sometimes referred to as the alfalfa ladybird, Subcoccinella has a very wide distribution; Palaearctic and east through Asia but not, apparently, in China, and south through North Africa. Introduced to North America during the twentieth century and now widespread, in many places common. In the U.K. it is generally common or even abundant throughout England and Wales north to Cumbria including the islands with the exception of Man. Further north there are a few southwest coastal or estuarine records from Scotland. Adults overwinter in grass tussocks, leaf litter among grass, gorse bushes or under dock leaves or debris. They are active during mild winter spells and are among the first coccinellids to appear. Sweeping grass will generally produce them in numbers from late February or early March. Adults appear commonly on flowers, especially apiaceae but also noted on thistles, nettles, mugwort, salad burnet, knapweed, spurrey and tansy. A wide range of food plants have been listed; seventy species in the U.S.A., mostly Caryophyllaceae and Fabaceae, and it is a pest, sometimes a serious one, of alfalfa, Medicago sativa Linnaeus. In the U.K. it has been recorder feeding on red campion and false oat grass. Preferred habitat is grassland in just about any situation, where the adults may be swept in large numbers from late spring until the autumn. In our local area they are abundant everywhere most years, and we have also swept them from salt marsh vegetation (Keyhaven, Hants.) Eggs are laid among low vegetation during May and the larval stage lasts about six weeks. New generation adults appear from the end of June, they may enter reproductive diapauses towards the end of July but they remain active into October or November. This diapause is initiated by photoperiod and temperature. Mortality during overwintering is high and overwintered adults finally die off in May or June. Our cool, temperate climate limits the population size and so the species does not become a serious pest. Specimens examined in the U.K. have been wingless; in a European study 40% of individuals were wingless but as winged specimens carry the genes for wing atrophy, it is thought that the wingless state will increase.

Subcoccinella is very distinctive and will quickly be recognized in the field. Henosepilachna argus is similar in overall morphology but is so much larger that this alone will separate the two species.

3.5-5mm. Entirely orange, each elytron with 11 dark marks which vary in number and size and which may be completely missing. There is a rare melanic form, f.nigra. Pronotum with various dark marks, typically one in the centre and one either side but these may be fused so that the surface is dark with pale margins. Entire upper surface with dense, very fine and pale pubescence. Head transverse and with well developed temples. Eyes entire, not notched along front margin. Clypeus narrowed in front of eyes so that the antennal insertions are visible. Antennal club well developed, terminal segment truncate.  Mandibles with four teeth at apex, deeply indented. Pronotum transverse and highly arched. Front angles produced forward. Broadest at hind angles and with hind margin evenly curved. Scutellum triangular and dark. Elytra very convex and with weak side margins. Underside mostly dark, punctured and shiny throughout. Without microsculpture and pubescent throughout. Prosternal process roughly punctured and produced to a point. Anterior margin of mesosternum evenly curved and strongly bordered. Anterior margin of metasternum straight and very strongly bordered. Tibiae angled on outer side towards apex. Each claw with a strong tooth at base.

Larval characteristics: Colour dull green-grey. Suture on front of head capsule an inverted Y-shape. Pronotum with four spines along the front margin. Meso- and metathorax each with a single seta-bearing tubercle low on each side.

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