It should drive me batty, right?

I used to give bats no more thought than most folks do. They were just another interesting critter I caught fleeting glimpses of as they flitted about at dusk.

Then I moved to Malta, home to the northernmost colony of migrating little brown bats in North America, and I became intimately familiar with them. The 100-year-old stone house we bought there was bat central. Trim was missing on a couple of second-floor windows giving them entry into the house, and while remodeling the place I found guano packed tightly between the rafters.

I carried the guano out to the garden in 5-gallon buckets,...