Lesser larch bark beetle - Orthotomicus laricis (Fabr.)



From: 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.



Occurrence: Europe, extending far behind the polar circle, also Siberia, Korea and Japan.

Host plants: The Scots pine and Norway spruce, rarely other conifers.

Morphology: Beetles are 3-4 mm long, dull, with short hair. Margins of elytral declivity are with 3 clear teeth on each side. A distance between two upper teeth is the same as between the upper and the second one. Females have less clear teeth.

Biology: O. laricis has two generations per year. Adults of the first generation initiate flying in May, and those of the second generation - in late-July - early-August. It is a polygamous species. After mating, females tunnel short egg galleries. Females lay eggs in clusters (about 50 eggs in each) on one or both sides of galleries. First, larvae feed together, then make individual, crossed with others tunnels. They pupate in the bark. The newly-formed adults have maturation feeding near their pupal chambers. Beetles of the second generation overwinter also near their pupal chambers. Occasionally overwintering occurs under the thick bark of pine stumps, or in short galleries made in the basal part of big dead trees.

Damage: O. laricis kills weakened trees. Often it infests the stored timber. It also can be a vector for the blue-stain fungi. This species prefers 30-100 year old stands and trees with the thick bark.

Preventive measures and control: Debarking of the stored timber or removal from the forest.

Diagram, Adult and galleries, Poland
Image by Robert Dzwonkowski

Damage, Boring dust resulting from larval feeding on slash
Image by Stanislaw Kinelski

Damage, Attacked spruce slash
Image by Stanislaw Kinelski

Adult(s), In gallery
Image by Stanislaw Kinelski

Galleries
Image by Stanislaw Kinelski

Galleries, With adjacent fungal infestation (white)
Image by Stanislaw Kinelski

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