Meet The Tiny Beetle That's Killing Off Grizzly Bears

It's hard to think of too many animals that could take out a grizzly bear.

At nearly 1,000 pounds and standing up to eight feet tall on its hind legs, the razor-toothed beast seems immune to all but the fiercest of contenders — and yet, one of the biggest threats to grizzlies is a tiny animal, hardly bigger than your fingernail.

Meet the mountain pine beetle.