Lodgepole pines killed by Mountain Pine Beetles (Dendroctonus ponderosae). All over the West, millions of conifers are succumbing to infestations of pine beetles. In this photo, the brown trees are dead or dying as result of damage by beetle larvae. Normally, hard cold winters kill most of the larvae, preventing damage to the trees. But unusually warm winters for the last ten years -- possibly related to climate change -- have fueled beetle infestations and the destruction of forests. Rocky Mountain National Park. Grand Co., Colo.