Linked from
The 18 pages that link to Bark beetle, each with the reason it gives.
ConiferRelated: Outbreaks can kill large numbers of conifers and alter forest structure.
PinusRelated: Bark beetle outbreaks can kill large numbers of pines and transform forest structure.
Abies albaRelated: Some bark beetles attack firs, especially when trees are weakened.
Picea engelmanniiRelated: Spruce beetle outbreaks can kill large numbers of Engelmann spruce.
Pinus lambertianaRelated: Drought-stressed sugar pines can become vulnerable to bark beetle attack.