Dorcatoma dresdensis Herbst, 1792
POLYPHAGA Emery, 1886
BOSTRICHOIDEA Latreille, 1802
DORCATOMINAE Thomson, C.G., 1859
Dorcatoma Herbst, 1791
Among the most widespread and frequently recorded members of the genus this species has an almost Palaearctic-wide distribution, it is also often quoted as being widespread in North America although these records may refer to D. falli White, 1965, and just to make life simple it is possible that both names refer to the same species. The European distribution extends from the Pyrenees through Northern Italy to Bosnia and northern Serbia and north to the UK and beyond the Arctic Circle in Fennoscandia; it occurs from lowlands to middle mountain altitudes and is locally common throughout. In the UK it is locally common across Southern and Central England and very sporadic and scarce in Wales and Ireland although because of its size and habits the species is likely to be under-recorded. Adults are active from April until September although specimens often occur earlier or later, and they peak in abundance between late May and early July. Typical habitats are all types of woodland, wooded parkland and pasture and it often occurs on individual mature trees in hedgerows and gardens etc. The species is usually associated with sporocarps fruiting on a wide range of deciduous and, less often, coniferous trees, it is a generalist and any fungus is probably worth investigating for adults during the summer. Recorded host fungi include Fomes fomentarius (L.) Fr. 1849, Phellinus igniarius (L.) Quél. (1886), P. lundellii Niemelä (1972), P. populicola Niemelä (1972), P. nigricans (Fr.) P. Karst, P. tremulae (Bondartsev) Bondartsev & N. Borisov, P. pomaceus (Pers.) Maire. (1933), Inonotus dryophilus (Berk.) Murrill, (1904), Inocutis rheades (Pers.) Fiasson & Niemela, Ganoderma applanatum (Pers.) Pat. and Mensularia radiata (Sowerby) Lázaro Ibiza, and we have found them on Laetiporus sulphureus (Bull.) Murril (1920) in a local Watford park. Mating occurs from late spring and larvae develop in mycelia-infested decayed wood or within sporocarps. The species is univoltine with winter passed mostly in the larval stage and pupation occurring from late winter to produce teneral adults from March or April. The nocturnal adults are easily spotted on the surface of trunks etc but they should always be taken for critical examination because other members of the genus occur in similar situations. Dispersal by flight occurs in the spring and so adults often occur in suitably placed flight-interception traps, at this time females actively seek out fresh host material and following their arrival they will remain on or near the fungus as they release pheromones to attract males. Populations tend to persist as long as suitable host material is available but large populations of Diospilus dispar (Nees, 1811) (Hymenoptera, Braconidae), a specialist parasite of the species, may eventually develop to control them.
Dorcatoma dresdensis 1
Dorcatoma dresdensis 2
© Lech Borowiec
2.9-4.1 mm. A broad and elongate species with strongly narrowed forebody and nearly parallel-sided elytra, body finely punctured and pubescent, shiny black to dark brown or with the elytra a little lighter, appendages reddish-brown. Head transverse, flattened between round and strongly convex eyes and rather densely punctured and pubescent throughout. Antennae 10-segmented, the basal segment elongate and strongly broadened, almost angled, internally and the last three segments massively developed; in males segments eight and nine strongly serrate (much wider than long) and the terminal segment more elongate, in females segments eight and nine broader and less strongly serrate and the terminal segment less elongate. Pronotum widely transverse, broadest across acute posterior angles and strongly narrowed to a rounded apical margin, basal margin sinuate and the surface finely and densely punctured throughout. Scutellum quadrate or slightly transverse, broadest across the base, sinuate laterally and weakly curved across the apex. Elytra with rounded shoulders and slightly constricted about the middle above the lateral margin so that the outline looks uneven, apical margin continuous and very narrowly explanate, surface sometimes uneven towards the suture, otherwise smooth, finely and evenly punctured throughout. Pubescence short, pale and decumbent throughout. Legs short and narrow with all femora and tibiae of roughly equal width and length, middle and hind tibiae with an extremely fine apical spur. Tarsi 5-segmented, short and with most segments quadrate or transverse, claws strongly curved, tiny and inconspicuous.