How do bark beetles attack?

Bark beetles attack stressed trees by boring holes into the bark. A normal, healthy tree would be able to fend off attack by exuding pitch into the holes pushing the beetle out. But drought- stressed trees have a difficult time producing enough pitch to fight off insects. Compounding the problem, beetles release pheromones that attract other beetles. This mass influx of beetles can quickly overwhelm a tree. Bark beetles are also attracted to freshly cut wood.