Pine beetles are a recent phenomena to forestry in North America. Only the size of a grain of rice, it burrows under the bark of pine trees eventually killing the tree. Thought to be a cyclic phenomena (historical records indicate similair incidents around the world in past), caused by a combination of climate and forest conditions. Little can be done to control these outbreaks. Vast ares of forest are affected.
The dead standing timber becomes a hazard for fires and people (weakened trees are blown over in wind storms)..
Logging dead timber, using it for products and re-planting seems to be the only current solution.