Forest Pests: Insects, Diseases & Other Damage Agents

Smaller european spruce bark beetle - Pityogenes chalcographus L.

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, the northern Asia, Korea and Japan.

Host plants: The Norway spruce, but often the Scots pine, sporadically firs and other conifers.

Morphology: Adults are 2.0-2.5 mm long, shiny, elongated, dark brown or black. Elytrae are bicolor - dark at the base, reddish-brown in remaining part. There are three pairs of teeth on elytral declivity. They are distinct in males and slightly visible in females.

Biology: Overwintering occurs in imaginal, occasionally larval or pupal stage. This species has one or two generations per year, in dependence on the weather conditions. Adults of the first generation fly in April-May. Adults of the second generation fly in July-August. There are 3-8 egg galleries running outward from the nuptial chamber that makes the whole feeding area star-shaped. Egg galleries are up to 6 cm long and 1 mm wide. Larval galleries are 2-4 mm long and dense. Galleries are well marked in the sapwood of thin segments of trees. In the part of stems with the thin bark, larvae pupate in the sapwood, and in the part of stems with thick bark, pupation occurs in the phloem. Young beetles have maturation feeding in and around larval galleries or sporadically on young shoots.

Damage: P. chalcographus is one of the most dangerous pests of Norway spruce. It often occurs together with Ips typographus and infests the upper part of trees, while I. typographus attacks the middle and lower parts. This species is of a high importance in young stands weakened by defoliators, where can occur and cause damage itself. At high density population, it attacks also healthy trees, therefore preparing the breeding material for I. typographus. It can infest small-sized timber and windthrows. This species prefers sites only slightly exposed to the sunshine.

Preventive measures: Removal of windthrows, tops and branches of cut trees and weakened trees.

Control:

• the use of trap trees with branches or groups of branches themselves in two periods: in late-March and in late-June - early-July;
• the use of pheromone traps: 1 trap per ha in slightly infested stands or in groups of 2-3 traps in moderately and heavily infested stands. Traps should be located in sunny places at the edge of the forest. A distance from the trap and the nearest tree should be minimum 10-15 m in young stand and 5 m in old stands. It is recommended to hung traps as high as possible;
• exposure of tops and branches baited with the pheromone and sprayed with insecticides. It should be done before the flight period of beetles.

Diagram, Adult and galleries, Poland Image by Robert Dzwonkowski	Damage Image by Stanislaw Kinelski
Galleries Image by Stanislaw Kinelski	Galleries, In upper part of tree Image by Stanislaw Kinelski
Galleries Image by Stanislaw Kinelski	Galleries Image by Stanislaw Kinelski

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