Bark beetle situation has eased further in Switzerland

While the damage caused by the spruce bark beetle - the most damaging species of bark beetle for spruces - decreased across the country, the situation worsened in individual cantons.

Last summer, around a third (34%) less wood had to be forcibly harvested across Switzerland compared to the previous year. Forced harvesting refers to the unplanned, short-term felling and utilization of infested trees.

According to the WSL, the total amount of wood infested by spruce bark beetles, including that which had to be forcibly harvested in winter and that which was left standing in the forest, fell by around 27 percent to 415,000 cubic meters in 2025. This would still be enough to fill over 5,000 SBB freight cars or the entire Lake Oeschinen. At the same time, a 24 percent reduction in the number of infestations was also recorded.

The infestation had already decreased in many regions in the previous year.

Regionally exacerbated situation

While 18 cantons, including Jura, Basel-Landschaft, Zurich and Aargau, recorded declines, infestations increased in seven cantons. The strongest increases were recorded in the cantons of Graubünden, Glarus and Valais, according to the specialist publication "Waldschutz aktuell".

The WSL cited the large amounts of wet snow, which led to severe snow pressure damage in the forest, particularly in the canton of Valais, as one of the reasons for the increases.

In particular at locations that were damaged by the weight of the snow last year, consistent monitoring and rapid control of new infestations will also be key in 2026 in order to prevent major damage, according to the WSL. Small, scattered and well-shaded areas are particularly susceptible to bark beetle infestations,