I discovered late this fall that voles had made their headquarters right under my prized Japanese tree lilac. I tried putting snap traps out with no success. Apparently they are very smart little buggers. I understand they do not hibernate and could literally eat the roots of my tree over the winter. Anyone know how to get rid of them in the wintertime? When we had a snow melt I could see all their squiggly trails. Never had these in my yard before. How awful! Help?