The spruce bark beetle is a small insect, growing only 4–5 millimeters long. During mass reproduction, however, they are capable of killing large spruce trees and entire spruce stands.

Cooler and wetter summer weather has helped reduce their numbers, and the number of the beetle's natural enemies has also grown.

The spruce bark beetle is monitored across Estonia by the Environmental Agency in cooperation with the State Forest Management Center (RMK). In some counties in South Estonia, the Estonian University of Life Sciences also operates its own monitoring stations. Both the university's data and nationwide monitoring results show that the beetle's population has been declining over the past two years.

The beetle's population was very high in 2022 based on RMK and agency monitoring data, said Merit Ehrpais, senior specialist at the Environmental Agency.

In 2023, the population remained high, but a downward trend began to appear in some counties. In 2024, the decline became clearer, and the 2025 results were even lower than those of 2024.

Kristjan Ait, junior researcher in forest management and forest ecology at the Estonian University of Life Sciences, added that based on this year's available data, the catch numbers are relatively modest. One direct factor influencing beetle numbers is Estonia's summer weather.

"Last summer was generally cool and rainy, which kept the population lower. This year's spring was also extremely unfavorable for the beetles: their flight began quite late, in early May," he said. Typically, the beetles begin flying in mid‑April. This year's spring dragged on, remaining cool and rainy, which further affected beetle numbers.

Ehrpais confirmed that results from pheromone traps show a clear link between weather and beetle activity. During cooler, wetter, and windier weeks, beetle spread is lower, while warmer periods bring higher numbers again.

In addition, the number of the beetle's natural enemies — such as bark beetle flies, ant beetles, and birds — has increased over the years. Their numbers have reached a level where they can now limit the beetle population more effectively.

Meelis Matkamäe, chairman of the Estonian Private Forest Union and CEO of Rakvere Forest Cooperative, has also noticed that there have been fewer beetle outbreaks in the past two years.

"The last two years have been quite good, especially in managed stands. The spruce bark beetle mostly infests weakened trees, and in a properly managed forest it is generally difficult for the beetle to establish a colony. But in unmanaged stands — for example those with storm damage or weakened trees — it can operate more freely, and conditions for reproduction are much better," Matkamäe said.

Ait added that managed forests offer better opportunities to limit beetle numbers, and mixed stands also provide poorer breeding conditions for them.

What will happen to the beetle population in the future is impossible to predict. "Right now the situation is fairly normal, but nature is constantly changing. What will happen in a couple of years, we don't know. Many influencing factors are things you can't directly see. For example, how root rot develops and affects spruce health, or whether new drought periods or storm damage occur — any of these could turn this calm period upside down," Ait said.

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