Four years since windstorm Vaia hit Trentino, an event that was never seen on the southside of the Alps, a new threat faces Trentino’s forests. This time it is a phytophagous insect called the bark beetle (Ips typhographus). It measures only a few millimeters but poses a major threat. If storm Vaia, in October 2018, caused 4 million cubic meters of crashed wood in the whole Province of Trento, the bark beetle has already affected 1.47 million cubic meters of trees over a total area of 8350 hectares. And the count of dead trees does not seem to stop .
Under normal conditions, the beetle attacks and reproduces in weak plants, especially spruce trees, thus contributing to the forest cleanup. It therefore plays an important role in the forest ecology because it attacks plants that have reached the end of their life cycle. Nonetheless, thanks to the huge availability of groundwood generated by the windstorm and weather patterns that favor very hot and dry temperatures, the insect has also been attacking plants that survived the storm: they are now weak and vulnerable. Both bark beetle adults and larvae dig tunnels under the tree bark, interrupting the flow of sap and virtually killing the plant. The consequences are easily seen by looking at the crown color of attacked spruce trees: it goes from amber yellow to rust red. In the final stage, the tree loses all its needles and acquires a gray color. Before it turns gray, the insects move away, leaving the tree to its rapid death.