Perhaps you've visited a restaurant and seen clear, water-filled bags hanging on the doors or cinched up in the outdoor dining area. You might ask, "What's all this about? Some crazy new way to control temperature? A scheme to save money on water pitchers?"
While any effect on temperature is purely accidental, these hanging bags are all about driving pests away. People hang these bags outside their homes, businesses and even in their barns to drive flies away.
Various takes on the water-bag practice exist. Some advocates insist the bag must have flakes of floating tin foil; others say a single penny. A couple of industrious Web sites even offer commercial takes on the concept, selling specially designed water bags to be used as repellents.
Flies spend much of their time buzzing around such germ havens as dumpsters, carcasses and animal droppings. Then, loaded down with germs, these flies swarm around your chicken sandwich -- it's only natural that you'd want to keep them away. After all, flies aren't just annoying, they carry diseases.
But how can a bag of water help? Does it even work? Experts and amateurs alike are split on the question. On the next two pages, we'll examine both sides of the issue.