Much to our surprise, two years in a row, this trick has worked. We kept having wasps by our clothes like and our rocking bench on our patio. Last year we put up the little bag with a penny and *POOF!* no more wasps there!
The bag then leaked, and this spring we had wasps again. My husband put up new bags, and we haven't seen a wasp since. I have no idea why it works, and I'm still surprised that it does. But, hey, it works, so I'm happy! (Doesn't work on the flies or the mosquitoes for us, but it does for wasps, oddly enough!)
What random, weird tricks have surprised you by working?
My mother found an old farm house trick of painting the undersides of eaves and porches sky blue to keep them from building nests there. We still get the occasional wasp starting a nest on the red trim, but none on the blue portions. We dozens of species of wasps, with high populations.
Amateurs built google. Professionals built the titanic. We can't find the guy that built this tiny ad: