Spruce bark beetle numbers in Estonia fall for second consecutive year
The population of spruce bark beetles in Estonian forests has declined for a second straight year, driven largely by cool, wet weather and a growing number of the insect's natural predators.
Spruce bark beetle numbers in Estonian forests, which were still rising three to four years ago, have been trending steadily downward in recent years. The tiny insect, only 4–5 millimeters long, is nonetheless capable of killing large spruce trees and entire spruce stands during periods of mass reproduction.
The beetle is monitored nationwide by the Environmental Agency together with the State Forest Management Center (RMK), while the Estonian University of Life Sciences also runs its own monitoring stations in several South Estonian counties. Data from both sources point to a two-year decline.
According to Merit Ehrpais, senior specialist at the Environmental Agency, the beetle population was very high in 2022 and remained high in 2023, though a downward trend began appearing in some counties that year. The decline became more pronounced in 2024, and 2025 figures were lower still.
Kristjan Ait, a junior researcher at the university, said this year's catch numbers are relatively modest. Last summer was cool and rainy, which kept numbers down, while this year's spring was particularly unfavorable for the beetles — their flight period only began in early May instead of the usual mid-April.
Pheromone trap data confirm a clear link between weather and beetle activity, with cooler, wetter and windier weeks bringing lower spread and warmer periods bringing it back up. At the same time, the number of the beetle's natural enemies — including bark beetle flies, ant beetles and birds — has grown enough to more effectively curb the population.
Meelis Matkamäe, chairman of the Estonian Private Forest Union, noted that the beetle mainly infests weakened trees, making it harder to establish colonies in well-managed forests, whereas unmanaged stands with storm damage offer much better conditions for it to spread. Ait added that mixed forest stands also make poorer breeding grounds for the insect.
Experts caution that future population trends remain unpredictable, since factors such as root rot, drought and storm damage could still reverse the current calm.
