There's a mystery afoot, my dear Watson

In some parts of the US, there's been reports that trees aren't bearing acorns this year. "We're talking zero. Not a single acorn. It's really bizarre," said Greg Zell, a naturalist at Long Branch Nature Center in Arlington.

Then calls started coming in about crazy squirrels. Starving, skinny squirrels eating garbage, inhaling bird feed, greedily demolishing pumpkins. Squirrels boldly scampering into the road. And a lot more calls about squirrel roadkill.

But [field botanist Rod] Simmons really got spooked when he was teaching a class on identifying oak and hickory trees late last month. For 2 1/2 miles, Simmons and other naturalists hiked through Northern Virginia oak and hickory forests. They sifted through leaves on the ground, dug in the dirt and peered into the tree canopies. Nothing.

Simmons thinks the reason could be that the unusually heavy rainfall in the spring washed the pollen out of the air before it had time to pollinate the acorn blossoms. But Ed Zimmer, a regional forester for the Virginia Department of Forestry, doesn't think that's possible. So far, no one knows for sure what's going on.

Where'd all the acorns go?