These beetles burrow through the outer bark of conifers, lay eggs which hatch into hungry beetle larvae, which then consume the living inner bark of the trees. Currently western pine forests are affected, especially lodgepole pine. There are 17 species of native bark beetles in Rocky Mountain National Park alone.
Hard winters can kill beetle eggs and larvae which winter under the outer bark, but it has to be bitterly cold to work. Unfortunately the average winter temperatures in affected areas has not been cold enough - with higher than normal temperatures reported over the past ten years. Reports say this is due to over-all global warming.
Cutting down the affected trees will not necessarily cure the problem, at this point. By the time trees turn red or brown, the beetle has moved on to another tree, and/or area. With this comes increased risk of forest fire, with dead timber fueling the fires throughout the region.
Park services are doing what they can, removing trees containing the live beetle, hazard trees have been removed from developed areas of parks, as well as from back-country areas, and spraying is also being used. There have also been temporary closures in certain parks, or areas of parks, until locations are determined to be safe to reopen.
One interesting upside is the use some are finding for the fallen timber. We have noticed a number of products available, with the distinctive marking of the bark beetle. The beetles leave a blue ring within the tree, visible and even decorative. As they push out the sap, killing the tree, this ring becomes a hallmark of the demolition. Some of the dead tree is then resurected as stools, benches, and other interesting furniture and decorator items. Another way we can take "waste" and turn it into a resource!
Another positive result of this infestation is the fact that as some trees die, there is more room for the undergrowth to grow. Just as a forest fire can be good as it releases seeds and increases new growth of pines and a variety of other vegetation, the same is happening as these infested trees die. Of course, the need to keep infestation down is apparent, but often good does come from bad in nature.