Nestled in the spruce trees in the Harz mountains of northern Germany is a bark-eating pest not much bigger than a sesame seed.
Known as “book printers” for the lines they eat into the bark that fan out from a single spine resembling words on a page, these eight-toothed beetles have always been part of the local forest. Officials expect the bugs to typically kill a few spruces each summer as they find suitable trees to lay their eggs — they burrow into the tree’s cambium, or growing layer, hampering it from getting the nutrients it needs to survive.
