The volume of spruce wood affected by bark beetles has decreased for five consecutive years, but it is important to also consider other tree species
Last year was notably better for forest protection compared to the years at the end of the previous decade, as indicated by records of harmful agents affecting forests. The 2025 report, which the Forest Protection Service received from an area representing 69% of the total forest land in the Czech Republic, showed a significant year-on-year decrease in forest damage.
Data collected by the Forest Protection Service indicate a significant year-on-year decrease in tree damage, dropping from 4.6 million m³ of wood mass in 2024 to 3.0 million m³ in 2025. Approximately two-thirds of the damage is caused by abiotic factors, primarily wind and drought, while the remaining third is attributed to biotic factors. Although damage to spruce trees has decreased by around 45% compared to 2024, other coniferous trees, particularly pines and firs, have experienced increased attacks from bark beetles. Among deciduous trees, ash has also been affected.
The situation for Norway spruce has remained stable for many years, with the primary threat being the spruce bark beetle. This beetle is often found alongside the northern bark beetle, and in the upper parts of the stem, it is also affected by the spruce wood engraver. In contrast, the species composition of bark beetles and wood-destroying insects affecting pine trees is much more diverse. In Moravia, the lesser pine beetle is predominant, while in Bohemia, both the pine jewel beetle and the wood wasp (Sirex noctilio) are present.
New pests are emerging, and RNDr. Petr Doležal, Ph.D., the Head of the Forest Protection Service, reports: “Over the last two years, the bark beetle species Orthotomicus longicollis (Gyllenhal, 1827) has been spreading significantly. Last year, this species, which was previously unknown in Bohemia, became the dominant bark beetle on pine trees. In many areas, due to the earlier onset of spring swarming, it displaced the pine bark beetle from the lower parts of thick-barked stems. Additionally, in several locations, we observed an unusual infestation of this species in stands aged 20 to 40 years, likely due to a lack of other suitable material.”
In 2025, approximately 26,000 m³ of harvested pine bark beetle wood was recorded; however, the actual infestation of pine by bark beetles is significantly higher, as logging of dry trees often occurs with a delay of several years.
Another tree species that has experienced a year-on-year increase in bark beetle infestation is the silver fir. In 2025, the total volume of harvested wood reached 7.6 thousand cubic meters, compared to approximately 5.6 thousand cubic meters in 2024. This infestation was primarily caused by bark beetles from the genus Pityokteines, specifically the silver fir engraver, as well as weevils from the genus Pissodes, particularly the European silver fir weevil. Due to the lengthy period—often up to six months—between infestation and the visible colour change of the needles, many completely infested trees are often harvested before they are recognized as being abandoned.
It is important to highlight the significant prevalence of fungi pathogens in 2025. The amount of wood infested with woodworms reached nearly 25% of the volume of spruce bark beetle-infested wood. Foresters encountered leaf spot diseases more frequently, with needle cast and oak powdery mildew being the most notable. Unfortunately, there are no signs of improvement, as ash dieback continues to spread throughout the Czech Republic, primarily due to the fungal pathogen Hymenoscyphus fraxineus.
The diversity of insect pest species, which often have vastly different life cycles, along with the increasing severity of fungi pathogens, increases the demands on forestry personnel. This scenario emphasizes the importance of collaboration with the research sector and the various training and consultancy services provided free of charge by the Forest Protection Service.
More detailed information on the health of forests is available in the LOS 2026 Newsletter, which can be downloaded here.
Contacts:
RNDr. Petr Doležal, Ph.D., Head of the Forest Protection Service, VÚLHM, v. v. i., e-mail: dolezal@vulhm.cz
Ing. Bc. Jan Lubojacký, Ph.D., Forest Protection Service, VÚLHM, v. v. i., e-mail: lubojacky@vulhm.cz
Illustrative photo: Withering and drying pines, firs and ash trees, author Jan Řezáč