I read that ants use pheromones to create trails and communicate with each other. I figured I could discourage them by interfering with their communications.
So I hacked an old EPROM eraser and exposed portions of an ant trail to hard UV. I found that:1) The ants would avoid the area of the lamp.
2) Placing the lamp on top of the trail wasn't effective because the ants detoured around it.3) Spacing the lamp ~0.36 m (~14") above the trail (inside a large cardboard carton) appeared to degrade the pheromones sufficiently that the ants all disappeared within a day, after a couple hours of exposure. Several days later, the ants have not reappeared.
Obviously, if I had kids or pets, I would *not* leave a hard UV source running like that, but I found this little experiment interesting nonetheless.