Adalia decempunctata (Linnaeus, 1758)
This western Palaearctic species was formerly abundant throughout its range but has been in decline over the past decade, presumably, at least to some degree, due to competition from the invasive Harlequin Ladybird, a species known to predate the larvae of the 10-spot. Along with the 2- and 7-spot this was the commonest of our conspicuous U.K. ladybirds and remains locally common through England and Wales though less so further north. Adults appear during March on herbaceous plants e.g. nettles and docks, and soon become common, frequenting flowers of all kinds but especially umbels and hawthorn blossom, and appearing on walls and fence-posts etc. Compared with the 2-spot they are more arboreal, frequenting wooded habitats, hedgerows, parks and gardens etc. and can be abundant in urban situations and on coastal dune vegetation. They generally occur on deciduous trees, especially oak, sycamore, beech and willow but also, though much less frequently, on pine and spruce etc. Although diurnal they sometimes come to light and are frequent in moth traps in suitable situations. Mating occurs during April and May and oviposition continues through late May and June; small batches of eggs are laid on foliage, twigs or in bark crevices and the larvae emerge after a few days. Upon hatching the larvae consume the chorion before searching for prey and at this time they may be seen on the backs of aphids, sucking the body fluids as they move, larger larvae devour aphids and their eggs as well as other soft-bodied insects; they pass through four instars before pupating during July or August, often in bark crevices or under leaves. New generation adults continue feeding into the autumn before overwintering but in good years there may be a partial second generation and adults from both generations will overwinter together, usually among leaf litter etc, under bark close to the ground or in garden sheds etc., often in numbers and often alongside other ladybirds. On the continent there are usually two generations each year.
Freshly eclosed adults are pale ochre and lack any darker markings but these soon develop, colour variation is very wide but most specimens conform to a few basic patterns. The typical form is red to pale brown with five dark spots on each elytron although sometimes there is an extra one or two across the middle, including a scutellary mark which is not joined across the suture; one at the humerus, three across the middle and two near the apex. In form bimaculata the elytra are brown to black with a reniform mark below each humeral tubercle. Form decempustulata the elytra are black to brown with five pairs of large, irregular pale macula, that on the humeral angle often extending along the lateral margin. Intermediate forms occur but they are rare.
3.5-5.0mm. Habitus almost round, convex and glabrous. Head black basally and pale anteriorly, sometimes with contrasting spots. The pronotum is either dark with pale anterior and lateral margins, or pale with five or seven spots forming a loose M-shaped pattern. Elytra with a transverse fold before the apex although this may be only weakly developed. Antennae, mouthparts and legs pale. Underside black with the meso- and metepimera pale. Femoral lines not forming a semi-circle. Claws with a large basal tooth.