In Oregon, Swarms of Pine Butterflies Take Toll on Forests

Aired: 3/12/2012 | 0:06:44 | Clip
In Oregon's Malheur National Forest, pine butterflies experience a population explosion for two to three years every three decades. Oregon Public Broadcasting's Oregon Field Guide series explores the snowstorm-like population surge that has stripped needles from 250,000 acres of trees.