California: Why Tiny Insects Are Tearing Up Sierra Forests

Western pine beetles, native inhabitants of Sierra Nevada forests, typically go unnoticed. The grain-of-rice-sized insects live a quiet life, spent mostly beneath the bark of weak, diseased or injured trees. But the beetles of late have been causing an uproar. They have been decimating ponderosa pine trees throughout the central and southern Sierra, turning entire hillsides red — the color the pines turn just before they die.