According to Netherlands-based designer José de la O, the proprietors of outdoor taco kiosks in Mexico use an ingenious form of pesticide based on light; a plastic bag full of water hangs from the ceiling, amplifying colors and movements through the refraction of light. The fly's pick this up with their (many) sensitive eyes and keep their distance—it either scares or confuses them.
For Dutch Design Week, José has taken this traditional technology and formally revamped it, using a glass bottle and stopper in place of the plastic bag. As far as repellants go, this one is dramatic and quiet, keeping insects at bay instead of trapping or killing them on the spot .
To buy one, get in touch with José directly.