EEEEK! Do not use mothballs in the garden! Here's what Mike McGrath, former editor of OG, says in his column to a reader who questioned if she could use them to repel neighbors' cats:

"VERY IMPORTANT: Don't ever use mothballs or flakes. Those little toxic waste pellets destroy cats' kidney function, could seriously harm people who handle them, and yes, contaminate your garden soil. Their packaging even warns against using them this way. "

The main ingredient naphthalene, is a strong chemical that stays in your soil for a long time.

I had an idea that it might be able to do some harm so I was a bit wary to put it in my soil without finding out for sure...I greatly appreciate the info!

Not just cats, try people too.

Never put mothballs into your environment, inside or out.