Are moles in the garden a source for concern? Not necessarily, say Doc & Katy Abraham in their book, Green Thumb Wisdom: Garden Myths Revealed!. People have a false notion as to the damage moles do. They do not munch on bulbs or roots, but they do make tunnels in the soil in search of grubs and earthworms. When you see mole tunnels and missing bulbs or damaged plants, you should suspect field mice and voles (that is voles, not moles). These rodents use mole tunnels for protection and as avenues to food supplies.
A mole has a tremendous appretite and can eat half its own weight in food daily... There is no need to control them. If you kill off their food (grubs), they go elsewhere... If you don't like their tunnels, control moles by controlling the grubs that attract them to your lawn. You can purchase predatory nematodes at garden centers that will get rid of the moles' food supply -- this no more moles.
[Excavating around the foundation of the house, I discovered a huge colony of carpenter ants and a rather plump mole who had taken up residence nearby. The colony of ants was destroyed and the mole relocated... to the rose garden. He leaves those telltale ridges in the ground and in the beds! At first, I was annoyed. But, now that I understand moles a little bit better, (and this garden is cursed with a large grub population!) I am very happy for his presence. -- Alex Sutton]