When we were kids, my brother and I had the mother of all pillow fights. It ended with a shriek of glee when David swatted me squarely on the top of my head. His pillow burst, liberating thousands of feathers. For weeks afterward gypsy bits of white fluff roamed through our house, rising from dresser drawers, drifting out of folded clothes, and even, to my surprise, peeking out from the corner of a small red carton of cloves in the kitchen pantry.

But each time I tried to trap one of these...