I have never had to deal with voles, but I heard that morth balls stuffed into the tunnels would deter them. It might be worth a try.

Ron
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Try used coffee grounds (I mix it with shredded leaves). They don't seem to be too fond of the UCGs and stay away from the areas where I apply it in the gardens.

Hi, I had voles giving me a hard time a few years ago, ate all my Monarda roots and any seeds I put out. I got a live mouse trap, put some decon poison in it, and every few days had one of my boys empty out the fur and bones. Worked fantastic!

Good Luck
Karen