Answer: That's difficult because different creatures have different likes and dislikes, and what might work in one region doesn't work in another. The bottom line is if creatures are hungry and thirsty enough, anything is fair game. For most pests in the garden, you generally need to try a few different strategies, together and at different times, to keep the pests off balance. Animals are smart little critters and they can soon grow accustomed to our attempts to foil them! Having said that, here's some info that I hope gives you some ideas.
Moles don't usually eat plant matter, preferring insects. Rodents such as mice and voles use their tunnels like a subway, and they do eat roots and bulbs. Moles tunnels are usually marked by raised soil and a soil pile around the exit hole. If there isn't a heap like this near the hole, then your culprit is probably a mouse, chipmunk or vole.
Euphorbia lathyris, also called gopher plant or mole plant, has a poisonous caustic milky like sap that supposedly repels these critters. However, the sap is nasty for humans as well, so use caution around it. Moles evidently hate the smell of castor oil beans, and there are various repellents that include it. You could also try the plant itself, Ricinus communis, although its seeds are also poisonous. You could also try any strong-smelling plants as possible barriers, such as onions, society garlic, Mt. Lemmon marigold (Tagetes palmeri.
If you are trying to proof an entire landscape, that's going to be difficult. If you are trying to secure specific garden beds, you could plant the area in a cage of wire. You need to excavate the garden area to a depth of 18-24" and line it with an underground barrier of hardware cloth. If you splice pieces of the hardware cloth together to fit the space, be sure to overlap them to prevent a chink in your garden's armor! Overlap the corners as well. A great side-effect of this effort is a wellareated soil - you can use it as an opportunity to mix organic matter into your garden! This is labor intensive, but it depends on how bad your problem is. Good luck!
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