Trees hit by second highest bark beetle infestation 

The bark beetle sits between the bark and the wood in the tree and lays eggs there. The larvae that hatch from the eggs then eat the best layer of the tree. Keystone

The level of spruce trees in Switzerland damaged by the bark beetle last year reached its second highest level ever recorded, after the hot summer of 2003. 

In 2019, bark beetle damage affected 1.4 million cubic metres of spruce, of which an estimated quarter of a million is still standing, according to a survey by the Federal Institute for Forest, Snow and Landscape ResearchExternal link (WSL). This compares with 829,000 cubic metres in 2018.  

It is the first time since 2005 that the level of infested wood has reached over a million cubic metres.

The reason for this is probably that a third generation of beetles could develop at lower altitudes under the warm, dry conditions in autumn 2018, says the WSL. Millions of larvae hibernated in the bark of the spruces, weakened the trees and had a good start in spring 2019. The summer of 2019, the third hottest since the start of measurements, did the rest, with food and habitat in abundance for the bark beetle.  

The WSL recommends that forest services and forest owners remove infested wood “before the bark beetle flies out again in spring” to limit the spread of the beetle, which prefers relatively freshly dead trees.  

Spruce is the most important timber tree in Switzerland, and spruce forests often have a protective function in the mountains.