Nothing new in the woods Les Safranyik, a forest entomologist with the federal government's Pacific Forestry Centre in Victoria, B.C., is widely recognized as a leading expert on the mountain pine beetle. He points out that the beetle, which has always been a part of western North American forest ecosystems, from Mexico all the way to 56 o North latitude, wasn't always a major problem. That's when the troubles began. Mountain pine beetles launch their assault by boring into a tree's bark, carrying with them spores of the bluestain fungi. Eggs are laid in the tree, and together the beetle larvae and fungi cripple the tree's ability to transport water up its trunk.
Infected trees turn a characteristic red colour and eventually die.
Over the millennia, lodgepole pines and other victims of the beetle have evolved defences, of course. The bark resin of healthy trees can prevent infestation by destroying the beetle's eggs. But older trees don't produce as much resin, making mature stands of pines vulnerable to attack. Back when wildfires were allowed to burn themselves out, most forests were composed of a variety of ages of trees. Such forests could easily withstand pine beetle attacks.