U.S. Forest Service officials are reporting the second year of a significant drop in the number of tree deaths from bark beetles in western National Forests.

However, Rob Mangold of the US Forest Service says, there's an upside and a downside to the decline. "Due to the fact that the suitable host type, log pole pine, which is what's been principally affected by the bark beetle-mountain pine beetle, we are, sort of, running out of some of those stands."

So while the bark beetle infestation appears to have run its cycle and is winding down, it's because the insect has destroyed its favorite host tree.

Mangold says in 2009 there were about 11.8 million acres with some level of mortality. That dropped to about 9 million in 2010 and in 2011 it dropped again to 6.4 million acres of National Forest.