I have the same problen but they burrow under it to get into the
house, which is probably your case , they like it warm in winter, and
will eat through a 4x4 to make an entrance. Ever hear any noise in
your walls at night . Unless your house has no wood even a sill plate
they are inside. Check your basement near the holes. Nothing has
worked for me either. try pouring poison pellets down the hole. I am
going to try antifreeze in a tray covered by a box with a littlle
hole, so large animals dont get it . Honestly im at a loss , I have
at least 4 in here and the neigbors cat visits to hunt. Now here
will follow some amimal rights asstivists, Im worried about a fire
and them chewing my wires. Kill EM