Gnorimus nobilis (Linnaeus, 1758)
This species is widespread across Europe from Portugal to Greece and north to the UK and southern provinces of Fennoscandia, it occurs from lowland to lower mountain altitudes and is generally common in southern and eastern regions where many subspecies have been named but in Central and Northern Europe it is very local and has declined over recent decades die to habitat modification. In the UK it is widespread though sporadic and generally rare; two population strongholds are around the Kent and Essex borders and in the Severn Basin, especially in Worcester, but beyond these there are isolated records from e.g. Somerset, Cumbria and East Anglia and it is regularly recorded from the New Forest. It may well be more common than records suggest as adults tend to be elusive; they are diurnal and in hot sun will fly to various white flowers such as umbels or elder to feed on pollen and nectar but more generally they spend most of their time high up among foliage. The species is saproxylic with larvae developing among decaying wood in rot holes etc., in Europe it is recorded from a wide range of deciduous trees, often willows, hornbeam, ash, poplars and especially oaks, and in the New Forest is believed to feed within old oak and beech trees although here it has been recorded only as adults visiting flowers on road verges etc, but most modern records, especially in the west of its UK range, are from various fruit trees in old established orchards. Fully-developed adults are present year-round, they form from late summer and autumn pupae but remain inactive until late spring or early summer, they emerge during June and July and live for four to six weeks, they fly well and mate on flowers or trunks. Females seek out rot holes or areas of soft decaying wood where they burrow deeply into accumulated debris or pulp and lay individual eggs in small chambers, several eggs are laid at each site and each female is thought to lay about fifty in total. Larvae emerge after two or three weeks and develop for up to three three years, they feed on damp wood mould and produce characteristic faecal pellets which are distinctive enough to prove the species presence, they are of typical scarabaeiod form; white and c-shaped and measure up to 45 mm when fully-grown. Pupation mostly occurs in late spring and summer, larvae form oval cells from secretions and wood pulp and pupate within, this stage is brief and adults emerge soon afterwards, they feed for a while before breeding and this generation will die-off in late summer or early autumn, but the situation is more complex than this as adults have been recorded in all months from April until November. The species is easily reared under artificial conditions, larvae will develop and pupate among soft and damp wood and adults will readily feed on a range of fruits including banana and plum before mating, and females will oviposit among decaying damp wood, the eggs are spherical, about a millimetre in diameter and white with dark grey flecks.
Gnorimus nobilis 1
Gnorimus nobilis 2
Gnorimus nobilis 3
This species has been very rare and local in the UK over the late 19th century, it is thought to be ancient forest relict that has displaced over time from pioneer trees such as birch and willow to oaks and beech and, in certain areas, to cultivated fruit trees in old established orchards. For a while this may have increased the species range and numbers, indeed there are modern records from several orchards in Kent and Buckinghamshire which might support this, but the decline in traditional orchards and their replacement with more commercially attractive dwarf trees and trained plants is thought to have caused a more general decline over the latter half of the twentieth century.
15-20 mm. Large, broadly-oval and discontinuous in outline with the forebody much narrower than the broad and rounded elytra, entirely bright metallic green but for various small while marks to the elytra and pygidium. Head strongly punctured and roughly sculptured between convex and protruding eyes, with short and strongly converging temples and greatly expanded plate-like frons which expands narrowly across the front of the eyes, antennae short and only weakly dimorphic, the club slightly longer in males. Pronotum transverse, rounded in the basal half and strongly narrowed to a rounded and produced apical margin, posterior angles rounded and basal margin not closely approximated to the elytral base, surface strongly punctured and sculptured throughout and in many specimens with a fine longitudinal median groove, distinctly pubescent towards the lateral margins. Mesosternum not visible in front of the elytral humeri (c.f. Cetonia). Scutellum triangular and more or less equilateral, densely and moderately strongly punctured except towards the apex. Elytra curved and narrowly explanate from protruding shoulders to separately rounded apical margins, surface glabrous and finely punctured throughout, roughly sculptured and without striae although often with vague longitudinal ridges. Legs long and robust, middle and hind tibiae with two strong spurs on the inner apical margin, middle tibiae distinctly curved towards the base and expanded apically in males, simple in females, front tibiae strongly toothed before the apex in females, much less so in males. All tarsi with five simple segments and paired simple claws. Distinguished from Cetonia and Protaetia by the lack of ascending mesosternum and the form of the scutellum. Our other member of the genus, the very local and rare G. variabilis (Linnaeus, 1758), is shiny black and has a much less extensively punctured scutellum.
Body continuous in outline
Scutellum much larger and elongate
Pronotum broadest across the base