Valgus hemipterus (Linnaeus, 1758)
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POLYPHAGA Emery, 1886
SCARABAEOIDEA Latreille, 1802
VALGINI Mulsant, 1842
Valgus Scriba, 1790
The only European member of the genus, this very distinctive chafer occurs mostly in southern and warmer central regions from Portugal to Asia Minor, it is present on most of the Mediterranean islands and across North Africa but to the north is very local and sporadic, reaching into lowland areas of Poland, Denmark and Latvia but otherwise absent from the Baltic region. Occasional specimens have occurred in the UK since the 19th Century, including several very recent ones from the London area, it is also known from archaeological deposits and so may have formerly been native, but there is as yet no formal evidence that it has become established. It was first recorded in North America from Michigan in 1980 when a single elm (Ulmus Americana L.) log of local origin was found to contain more than 100 adult beetles, their mode of introduction remains unknown but it was almost certainly accidentally introduced with imported European timber. On the continent Valgus is active from April until July or August and peaks in abundance during May and June, adults occur in a wide range of fairly dry habitats, including urban areas, vineyards, domestic gardens and other disturbed places, and fly during warm spells to visit flowers where they feed on nectar and pollen and mating occurs. Females oviposit among moist decaying trunks and branches of a range of deciduous trees (In France they usually choose oaks, birch, elm and chestnut) and larvae develop through the summer. Pupation occurs among decaying wood or in the ground beneath during late summer and autumn and adults eclose soon afterwards but remain in situ until the following spring. In southern and central regions the species is generally common and usually occurs in numbers, they first appear on umbel flowers and blossom and in late May and early June may form large assemblages which later disperse. Similarly decaying trunks and logs may host large numbers of larvae and pupae during the summer. The species is very likely to become established in the UK, if it has not already done so, and so should be looked for on flowers, especially various Rosaceae and Apiaceae which it favours on the continent, in spring and early summer.
6.0-8.0 mm. Small but very distinctive and should not be confused with any other UK species; broadly elongate and discontinuous in outline, entirely black to dark grey or reddish-brown with patches of pale grey scales, pygidium and propygidium exposed, legs long and robust. Head small and rather flat with large convex eyes, a long and angled clypeus and emarginate labrum, antennae short and only slightly sexually dimorphic. Pronotum quadrate in males and slightly elongate in females, broadest near the middle and narrowed to rounded angles, lateral margin crenulate anteriorly, surface roughly sculptured and punctured and with two longitudinal keels from the anterior margin. Elytra quadrate to slightly transverse, gently curved from rounded shoulders to separately curved apical margins, lateral margin continuous and not emarginate below the shoulders, surface roughly sculptured with longitudinal depressions and fine raised lines. Pygidium and propygidium exposed in both sexes, in females with sparse pale scales, in males almost covered in pale scales except for two large dark areas on each. Front tibiae with five strong teeth along the external margin in sexes, middle and hind tibiae smooth and with strong internal apical spurs. Tarsi long and slender, the basal segment of the hind tarsi about as long as the next three combined. Claws smooth, equal in length and not appendiculate. Males are usually a little smaller and have more extensive pale scales than females. Females are readily recognized by the long and narrow ovipositor.