Environment

Climate change supercharges threat from forest-eating bug

Deep in the Finnish woods, the moss and blueberry shrubs hide a deadly threat to the boreal forests that are as important to the planet as the Amazon rainforest. With chunks of their bark peeling off and needles falling from dying branches, more and more trees are being killed by the spruce bark beetle, which is venturing further and further north with climate change.

The tiny brown insects attack the Picea abies, one of Finland's most common tree species, and can cause massive damage to forests. Burrowing through the bark to lay their eggs, the beetles eat their way around the spruce and kill it by stopping water and nutrients reaching the higher branches.

The beetles thrive on weakened trees. Hot summers mean there are more water-starved spruce, while warm winters mean there is no frozen ground to brace the trees against storms. Warm weather also speeds up the life cycle of the beetles, meaning they can reproduce faster.