Controlling spruce bark beetle damage: identification and most effective methods

How the spruce bark beetle damages a tree

The European spruce bark beetle (Ips typographus) is a bark beetle that damages spruce trees. It attacks weakened trees primarily, but when present in large numbers also healthy spruces. It digs tunnels under the bark, cuts off the tree's fluid flows and can kill the tree within a single growing season. In addition, it spreads blue-stain fungi, which reduce the quality of timber.

Reproduction and risk areas

Spruce bark beetle reproduction begins in spring when the temperature rises high enough. In warm summers it can have two generations, which makes the population grow quickly. Because of wind damage, drought and climate warming, the risk of spruce bark beetle damage has increased particularly in southern and south-eastern Finland.

The greatest risk sites are mature spruce stands, windthrown spruces, forest edges bordering felling gaps, and spruce timber stored along roadsides. Dry dead wood no longer serves as a breeding site for the spruce bark beetle, so removing it is not necessary for control purposes.

How to recognise spruce bark beetle damage

Spruce bark beetle damage can be recognised, for example, by the bore dust and resin leaks visible on the trunk, thinning of the crown, and needles changing from green to yellowish or reddish-brown. Under the bark, a tunnel pattern typical of the spruce bark beetle can be found.

The most effective control measure

The most effective control measure is prevention: spruces felled by storms and other fresh damaged spruces, as well as fresh spruce timber, are to be removed from forests in good time in accordance with the provisions of the Finnish Forest Damage Prevention Act. Regular monitoring of forests helps detect damage at an early stage and prevent it from spreading.