The other day I marked the top rims of cups containing special varieties to make them easy to spot in tubs. I used cheap pink nail polish (strong smelling, Sally Hanson Hard as Nails) and put a few dabs on the rims of special cups. While doing that I found a couple cups with about a dozen gnats hanging around them. The tubs were left open. The next day the gnats were all gone and I put up yellow sticky stakes but still no sign of gnats. It's been 3 days and not one gnat in sight. It looks like the smell chased them away or killed them.
If anyone tries this I'm curious to know if it works for them.
Thanks, Soni.