voles in perennial border
How do I eradicate or control the vole population in very large perennial borders?
Bucks County Pennsylvania
Eradicate is a pretty high standard and one that you will probably never achieve without paving over your property, which I hope you don't do. A more achievable standard is to reduce the damage to a tolerable level.
This document will help you review your options. Be sure to follow all state rules and follow any pesticide labels. http://www.ianrpubs.unl.edu/epublic/pages/publicationD.jsp?publicationId=100