Acanthocinus aedilis (Linnaeus, 1758)

Timberman Beetle

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POLYPHAGA Emery, 1886

CHRYSOMELOIDEA Latreille, 1802

CERAMBYCIDAE Latreille, 1802

LAMIINAE Latreille, 1825

ACANTHOCININI Blanchard, 1845

Acanthocinus Dejean, 1821

This cerambycid is more widely known as The Siberian Timberman as its range extends far north into Siberia and the species is adapted to survive extremely cold conditions. Unlike other longhorn beetles both adults and larvae are tolerant to freezing and, in the frozen condition, will survive cooling to below -37°C. More generally the species is very widely distributed; throughout Europe including Scandinavia, Caucasian Mountains and east to Siberia, Mongolia, China and Korea. In northern Europe it tends to be generally common and in many places abundant. In the UK there are records scattered through England, Wales and Scotland although they tend to be coastal in the west. The U.K. stronghold is the Scottish Highlands and it is likely that many of the records scattered elsewhere are the result of the commercial movement of timber. The spectacular adults are active from March to June or, exceptionally, into July. They are diurnal and active on pine logs in sunshine when males can be seen fighting head to head, rapidly pushing each other around until one backs down and leaves the area. They are strong fliers and quick to invade new areas. The main host is pine but other conifers e.g. Picea are occasionally attacked In general they infest dead, recently felled or weakened trees, stumps or thick branches and they prefer lower parts where the bark is thick, and adults emerge from oval emergence holes about 6-8mm x 3-4mm wide. On the continent the species sometimes becomes a serious pest of commercially-grown timber, traps are available for their control, and areas of felled forest may have the bark stripped from residual stumps as a preventative measure. Females find bark crevices or chew depressions into the wood before inserting the elongate, white eggs using the ovipositor as a drill to do so. Larvae feed under the bark forming irregular broad galleries several centimetres long and up to three centimetres wide, at first these galleries are filled with shredded bark but later on with white wood chips. The larvae are distinctive; up to four centimetres long, legless and slightly flattened, the overall colouration is creamy or yellowish white with two yellow spots on the pronotum. After about four months of development they pupate in chambers constructed within the bark or, if the bark is thin, within the surface heartwood. The pupa is distinctive, displaying the adult morphology. Adults eclose after two or three weeks and overwinter within the pupal cell.

Acanthocinus aedilis 1

Acanthocinus aedilis 1

Acanthocinus aedilis 2

Acanthocinus aedilis 2

Acanthocinus aedilis 3

Acanthocinus aedilis 3

Acanthocinus aedilis 4

Acanthocinus aedilis 4

♂ body

Acanthocinus aedilis larva

Acanthocinus aedilis larva

Among the U.K. fauna this species is very unlikely to be confused with any other. 12-20mm body length. A medium sized longhorn, subparallel and depressed dorsally, pale reddish grey or brown with two transverse macula on the elytra which are sometimes very pale and indistinct. Entire upper surface with short, recumbent pubescence and the elytra have small and random tufts of darker setae. The head is small with the anterior face virtually flat. The antennae are very long; up to three times the body length in the male and one and a half times in the female. Antennal segments bicoloured; dark brown apically and pale towards the base. Pronotum transverse with a large lateral spine just behind the middle. Four pale spots form a transverse row in the apical third. Elytra flat and subparallel; evenly curved to the apex. Longitudinal ridges usually visible, coarsely and almost densely punctured in basal half, more finely and sparsely apically. Transverse marks sometimes indistinct; the one behind the middle is usually more obvious and sometimes the entire elytra behind this mark are dark. The female has a conspicuous elongate and truncate ovipositor.

Acanthocinus Dejean, 1821

A Holarctic genus including around 30 species of very distinctive longhorns which, at least among the European fauna, are recognized by the drab appearance and very long antennae. Throughout the region, and especially in the U.S.A, some species of Leiopus Audinet-Serville, 1835 come close in appearance but so far as the European fauna is concerned, Acanthocinus is distinctive. The two genera may be separated on the form of the prosternum; in Acanthocinus the coxae are widely separated whereas in Leiopus they are very close together. The species undergo a typical cerambycid life cycle with larvae developing in the wood of dead or damaged trees, many species develop over one year and the larval stage may be brief. Most species feed on Pine although other conifer species are sometimes chosen and a few species feed on the wood of broadleaved trees. Several are occasional pests of stored timber, reducing its value and as a result have become established away from their natural distribution. Around 20 species are recorded from the Palaearctic region, 8 from mainland China and several more from Southeast Asia including Taiwan and Korea. The 8 North American species are all pine feeders and univoltine throughout their range. A. aedilis (L.), the only species to occur in the U.K, and A. griseus (Fab.) have the widest distribution, both extending throughout Europe to the far east of Russia, China and Korea.

Medium to large, 10-25mm, generally drab beetles with various lighter or darker markings to the elytra. Body flattened head quadrate and slightly convex, clypeus margined apically. Eyes with lower lobes oblong, usually longer than the genae; upper lobes widely separated. Genae parallel or nearly so. Antennal tubercles divergent, with bases contiguous. Antennae long and thin; 1.0-2.0 times longer than the body in the female, 2.5-4.0 times in the male. Without hairs on the inner side and with white pilose rings at the base of some segments. Pronotum transverse and convex with the lateral margins moderately or strongly tuberculate behind the middle, the tubercles sharply spined in basal third. Surface generally with deep punctures, dense pubescence, a raised callus either side of the middle behind the anterior margin and four pilose yellow or pale macula in the anterior half which form a transverse row. Elytra about twice as long as broad; subparallel or tapering towards the apex. Individually rounded or subtruncate apically. Sometimes (as in A. aedilis) with definite longitudinal ridges. Usually with large and deep punctures throughout although in A. carinulatus only in the anterior half. Pubescence depressed and dense, often forming spots or vittae along the costae. Without erect hairs. Legs robust, with clavate femora. Hind tarsi with the first segment longer than the remainder combined. Third segment of all tarsi deeply lobed. Abdomen normal in the male; in the female the last segment is heavily sclerotized, robust and produced into an ovipositor.

Species include:

  • A. aedilis (Linnaeus, 1758)

  • A. griseus (Fabricius, 1792)

  • A. henschi Reitter, 1900. Austria, Croatia, Italy and Macedonia

  • A. reticulatus (Razumowsky, 1789).  Southern Europe and Russia

  • A. hispanicus Sama & Schurmann, 1981.  Spain

  • A. meyeri Vitali, 2011. Portugal

  • A. xanthoneurus (Mulsant & Rey, 1852) Italy

  • A. carmelatus (Grebler, 1833). Occurs in Southern Europe, the Alps and Northern Asia

  • A. sachalinensis Hasegawa, 1996. Occurs in Russia and was formerly a variety of A. carmulatus

  • A. elegans Ganglbauer, 1884. Endemic to Iran, feeds on deciduous trees

  • A. hutacharerae Makihara, 1986. Oriental

  • A. sinensis Pic, 1916. Oriental

  • A. chinensis Breuning, 1978. Oriental

  • A. orientalis Ohbayashi, 1939. Oriental

  • A. annamensis Pic, 1925.  Vietnam

  • A. gundaiensis Kano, 1933. Occurs in Asia east to China and Taiwan

  • A. guttatus (Bates, 1873) Russia east to China, Japan and Korea

  • A. subsolona Wang, 2003. Oriental

  • A. tethys Wang, 2003. Oriental

  • A. validus Matsushita, 1936. Oriental

The following species occur in North America:

  • A. leechi (Dillon, 1956)

  • A. nodosus (Fabricius, 1775)

  • A. obliquus (LeConte, 1862)

  • A. obsoletus (Olivier, 1795)

  • A. princeps (Walker in Lord, 1866)

  • A. pusillus Kirby in Richardson, 1837

  • A. spectabilis (LeConte, 1854)

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