Tetropium fuscum

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Kingdom: Animalia
Phylum: Arthropoda
Class: Hexapoda (including Insecta)
Order: Coleoptera
Family: Cerambycidae
Genus: Tetropium
Species: T. fuscum
Scientific Name
Tetropium fuscum
(Fabricius, 1787)
Common Names

brown spruce longhorn beetle



Brown Spruce Longhorned Beetle can be found throughout the central and northern Europe and Siberia and has spread also in the mountains of the southern Europe. It is not known to exist in the United States but has been found in Nova Scotia, Canada.

Host plants

The beetle prefers both the Scots pine and Norway spruce, occasionally attacks the fir, Douglas fir, eastern white pine and Sitka spruce


Adults are black, 8-19 mm (1/3-3/4 inch) long. Pronotum is dull, with dense punctures. Wing covers (elytrae) at the basal part are covered with dense yellowish pubescence creating a wide band across. Eggs are elongated, slightly engraved on both ends, 1.4x0.4 mm (1/16 x 1/64 inch) in size. Larvae and pupae are rather similar with some different details in body structure.

Life cycle

Adults are active in June through August. Adults do not feed. Females oviposit singly into bark crevices. Larvae hatch 10-14 days later and bore to the phloem and cambium. Larvae feed under the bark and upper wood making galleries up to 2 cm (3/4 inch) wide, which are filled first with brown shredded bark, then with white shredded wood. Larvae molt 4 times and in autumn bore tunnels of 7x4 mm (1/4 x 1/8 inch) in size into the wood in depth of 2-5 cm (3/4 to 1 1/2 inch), where pupate in pupal chambers. Larval galleries and pupal chambers of both species are similar. Pupation occurs from early-May through late-June. Adults emerge several days after pupation through oval holes of about 7 mm (1/4 inch) in diameter. Development of one generation may take one or two years.

Plant Response and Damage

The beetle attacks and often kill weakened trees. Technical damage is made by constructing of pupal chambers. Infested trees are can be easily recognized in early autumn by signs of woodpecker activity. In spring next year trees fade.

Preventive measures and control

Restrictions concerning the presence of weakened trees in the forest. Infested trees should be cut and debarked. The use of trap trees is recommended in high density populations. Trap trees should be established by mid-May. They should be checked in June and July and debarked when larvae are still feeding under the bark, before they bore into the wood, usually in late-July.

Image Gallery


  • Kolk A., Starzyk J. R., 1996: The Atlas of Forest Insect Pests (Atlas skodliwych owadów lesnych) - Multico Warszawa, 705 pages. Original publication in Polish. English translation provided by Dr. Lidia Sukovata and others under agreement with The Polish Forest Research Institute.
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