Answer: 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. 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!
The only sure way of eliminating moles and voles is to trap them. You can be successful if you set the traps in the main runs rather than in lateral tunnels. Moles use the main run frequently, but the laterals go to sleeping dens and places where they pile debris. To find the main run put on your detective cap and carry a long, thin stick or metal probe. Start exploring the yard, trying to find the direction and location of a long, straight tunnel. Once you've eliminated the short runs and honed in on the main tunnel, carefully set your trap (scissors-type traps are most effective). Cover the top of the trap with a piece of plywood or sod to eliminate light or you'll scare the critters away. Properly set in the main tunnel, your trap should net you a mole. Empty the trap and reset it as often as necessary to get all of the moles.
A more permanent solution would be to plant your bulbs in wire mesh cages or try surrounding the bulbs with coarse gravel when planting. Repellents can also be applied to the bulbs before planting. Moles evidently hate the smell of castor oil beans, and there are products that use this.
You could also plant the entire bulb area in a cage! 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 well-areated soil.
I hope some of these ideas help!
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