Clytra Laicharting, 1781
Of the two British species C. laeviuscula is on average a little larger and has more extensive post-median elytral macula; in extreme forms they form a wide transverse band only narrowly interrupted at the suture, but both species are variable and the patterns and sizes overlap widely. The form of the pronotum is diagnostic; in laeviuscula the lateral margins are straighter, very narrow and not flattened, only very finely, if at all, punctured, and the disc is sparsely and very finely punctured. The lateral pronotal margins of quadripunctatus are more curved, broad and flattened, especially towards the base, rugose and rather strongly punctured, and the disc has a moderately dense mixture of fine and very fine punctures throughout.
Clytra laeviuscula Ratzeburg, 1837
This very widespread species is locally common throughout southern and central Europe, northwest Africa and almost the entire Palaearctic region east to northern India, China, Japan and Korea although the northern extent is limited and it is absent from Scandinavia and the UK; here it was recorded from several widely separated sites, Berkshire, Surrey and Perthshire during the late nineteenth century but has not been seen since that time and is now considered to be long extinct. The biology is much the same as for C. quadripunctatus; adults feed on a range of broadleaf foliage but show a preference for poplars and willows and they are sometimes abundant on hawthorn and blackthorn blossom. Larvae develop similarly in the nests of various species of Formica but here the larval case lacks the longitudinal ridges seen in quadripunctatus. On the continent adults are active from May to August.
Clytra quadripunctata (Linnaeus, 1758)
This widespread western Palaearctic species is generally common throughout Europe from the Mediterranean north to the UK and above the Arctic Circle in Fennoscandia and extending east into western Siberia. In the UK it is widespread though very local and is thought to have suffered a decline over recent decades, throughout England and Wales except for East Anglia, it is absent from southern Scotland but there are scattered records from the northern Highlands. The typical habitat is broadleaved and mixed woodland but adults may also occur on mixed hedgerows and shrubs or young trees on heathland, they appear during April and are present until late in the year, peaking in June, although they are short-lived, generally about a month. Freshly eclosed adults feed on the developing foliage of a wide range of young trees and shrubs e.g. alder, hawthorn, blackthorn, birch, oak and willow and visit a variety of flowers, usually close to ant nests in which the larvae develop, and during the warmest days of summer they may be observed in flight along wooded borders. Mating occurs on foliage during May and June and oviposition begins in June. Females position themselves on foliage close to ant nests and drop eggs onto the ground, these will picked up by ants and taken into their nests where the larvae will develop feeding upon detritus and the remains of insects brought back by the ants but they are also predatory, feeding upon the eggs and early stages of the ants; the female will cover each egg with faecal material by rolling it around with her hind tarsi within her abdominal cavity before dropping it, this protects them from the ants and they are ignored within the nest. Each female will produce up to 100 eggs and may move from nest to nest depositing them as she goes, much less frequently she will approach the ant nest and deposit the egg directly among the mass of vegetation; freshly mated females sometimes remain on the nest for a while absorbing odours, they may be attacked by the ants but remain in place with the legs and antennae retracted and eventually the ants ignore them, even when they venture onto another nest. Larvae emerge with about 20 days and immediately construct a case from excrement and soil particles, the case is smooth and elongate with several longitudinal ridges to the dorsal surface which converge at the rounded apex, these ridges are thought to facilitate the ants transporting the larvae along with other material should the nest be damaged, the larva protrudes its head from the open end to feed or may emerge almost entirely to walk about, carrying the case as it goes. Larval development is slow; it passes through 3 instars and continues through the following winter, and as it grows and moults it enlarges the case; during the following spring the fully-grown larva will seal the open end of the case and pupate inside at the base of the nest. Adults eclose within 2 weeks but remain in the pupal case for a few days before emerging and leaving the nest. Various species of Formica Linnaeus, 1758 have been recorded hosting Clytra in the UK but the usual host is the wood ant, F. rufa Linnaeus, 1758, beyond this they have been recorded, very rarely, from the yellow ant, Lasius flavus (Fabricius, 1782). Adults may be found by sweeping foliage near to ant nests or by carefully searching foliage or nest mounds; they are easily spotted in flight and have been recorded at light.
7-11mm. This large and colourful species might only be confused with the species mentioned above; elytra and at least 2 basal antennomeres pale, otherwise entirely black. Strongly convex and elongate, near parallel-sided and continuous in outline. Head only narrowly visible from above, mostly hidden within the thorax, eyes strongly transverse and weakly emarginate behind the antennal insertions, vertex flat or weakly depressed and finely punctured and pubescent. Antennae short; basal segment dilated internally, 2 & 3 quadrate or nearly so and 4-10 serrate. Pronotum transverse with wide rugose and coarsely punctured lateral and basal margins, broadest at perpendicular posterior angles and narrowed to obscure anterior angles, basal margin very strongly sinuate; surface with a mixture of fine and very fine punctures which are denser towards the base. Scutellum large, triangular and very finely punctured. Elytra orange, each with a dark mark at the shoulder and behind the middle, punctures fine and random or with a tendency to form rows on the disc, lateral margin sinuate and strongly bordered. Legs robust; tibiae sinuate externally and broadened towards the apex, tarsi pseudotetramerous with the third segment strongly bilobed.