Long-horn beetle (Arhopalus rusticus)

From Bugwoodwiki

Kolk A. and Starzyk J. R. 1996.The Atlas of Forest Insect Pests. The Polish Forest Research Institute. Multico Warszawa. 705 pp.


It is a common species in the northern and central Europe, Siberia, Korea, Mongolia, Japan and the northern China.

Host plants

Conifers, mainly the Scots pine and Norway spruce.


Adults are dark brown or brownish-red, dull, 10-30 mm long. The body is elongated and flattened, slightly haired. Elytrae are with 2 or 3 parallel ridges. Antennae of females are not longer than a half of the body and those of males are about 2/3 of the body length. The egg is white, elongated, of 1.9 x 0.5 mm in size. The larva is white, flatted, up to 28-39 mm long, with legs. At the end of 9th segment there are two characteristic spines (urogomphi) that are sharper than those of A. striatum. The pupa is up to 25 mm long.


Adults are active from mid-June through late-August. Mating occurs at a sunset. Females oviposit eggs in clusters (several eggs per cluster) into crevices of the thick bark. One female lays up to 800 eggs. Larvae hatch 2-3 weeks after oviposition and feed under the bark. After 4-6 weeks larvae enter the wood through oval holes of 0.75-1.5x1.4-4.0 mm in size and excavate tunnels of 6-7 mm in width. In dense populations, numbers of entrance holes reach up to 100 per 1 dm2 of wood. Galleries are filled with frass and pressed shredded wood and bark. Galleries are very similar to those of A. striatum. Larvae overwinter once or twice under the bark or in the wood. In spring or summer of the third year after mating, larvae construct pupal chambers and chew exit holes of 5-13x3-8 mm in size. The pupal stage lasts 14-21 days. Adults emerge through exit wholes. This species has one generation per 2 years.


It is a technical and physiological pest infesting mainly the basal part of tree stems up to 1.5 m. When abundant it can cause the tree dieback. The infested timber is of a little value. A. rusticus is a very common insect on stumps, where plays a positive role in wood decomposition.

Preventive measures

Removal of breeding materials from woodlands.


Removal of infested trees. The use of trap trees is also recommended. They should be placed 3 times: the first time - exposure in mid-May and debarking in late-June, the second time - exposure in mid-June and debarking in late-July, and eventually the third time - exposure in mid-July and debarking in late-August or early-September. Debarking of infested trees should be done before larvae enter the wood. The treatment of the wood with liquid insecticides at the moment when adults are ready to leave the tree.

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