Forest Pests: Insects, Diseases & Other Damage Agents

European spruce bark beetle - Ips typographus 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 and Asia Minor.

Host plants: The Norway spruce, occasionally Scots pine, larches and firs.

Morphology: Adults are 4.0-5.5 mm long, cylindrical and robust, black or brownish-black. Elytral declivity is slightly shiny, with 4 teeth on each margin side. The third tooth is the biggest and club like on its top. The egg is yellowish-white. The larva is white and legless. The pupa is also white.

Biology: Adults overwinter in litter or under the bark. Occasionally overwintering may occur in larval or pupal stage. Adults of the first generation are active in April-May, and those of the second generation - in July-August. In dependence on the weather conditions, this species has one or two generations per year, with one or two sister generations. After mating, 2-3 females tunnel vertical egg galleries from the nuptial chamber. They are not visible on the wood. Eggs are laid every 2 mm. Larvae chew galleries horizontally, and after feeding for 3-4 weeks, they pupate in pupal chambers in the bark. Young adults have maturation feeding under the bark making characteristic horn like tunnels well visible in the wood.

Damage: I. typographus is one of the most serious pest of the Norway spruce in mountains and lowlands. It attacks standing weakened and healthy trees, windthrows. It infests mainly lower and middle parts of stems. Attacked trees are easy to recognize by brown dust coming out of the bark and concentrating at the basal parts of stems. Living trees are killed as soon as cambium is destroyed by larvae. Sometimes trees with green crowns can be without the bark because of larval and woodpecker activity.

Preventive measures: Removal of all potential breeding material (logs with bark, weakened trees, windthrows etc.) from the forest in the period from October through April.

Control:

1. The use of trap trees three times: the first time - in March, the second time - in May, the third time - in June-July. They should be debarked when distinct larval galleries with small larvae occur;
2. Searching for, cutting and removing of all infested trees (with visible brown dust on stems and ground). These trees should be cut and removed from the forest together with adults in 2-3 weeks after the first beetles bore into trees;
3. The use of pheromone traps: 1 trap per 4 ha in slightly infested stands, 1-2 groups of 2-3 traps per ha in moderately infested stands, and 3-4 groups of 4-6 traps per ha in heavily infested stands. In healthy stands, a distance from the trap and the nearest trees should be minimum 15 m in lowlands and 30 m in mountains. In weakened stands, they should be 30 and 50 m, respectively;
4. The use of trap trees baited with pheromones and sprayed with an insecticide;
5. Chemical treatment of emerging beetles.

Diagram, Adult, pupa, larva and galleries, Poland Image by Stanislaw Kinelski	Damage, debarking tree Image by Stanislaw Kinelski
Adult(s) Image by Stanislaw Kinelski	Galleries Image by Stanislaw Kinelski
Damage, Boring dust on bark Image by Stanislaw Kinelski	Galleries, Fully developed galleries Image by Stanislaw Kinelski
Life Cycle, Larva, pupa, and young adults Image by Stanislaw Kinelski	Galleries Image by Stanislaw Kinelski
Trap(s), Trap trees Image by Stanislaw Kinelski	Trap(s), Borregaard trap in middle and funnel traps on side Image by Stanislaw Kinelski

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