Although moles are insectivores and eat little vegetable matter, voles are strict herbivores and readily feed on roots and bulbs of many kinds, often causing severe damage. This initiative was passed to regulate the types of traps legal in Washington state. This includes all commercially available mole and gopher traps, which are mentioned in WSU publications on mole management. There are many materials on the market and you can certainly try them, but they haven't been shown to be consistently effective. Don't kill earthworms in an attempt to reduce mole activity.
Earthworms are definitely beneficial garden inhabitants.
Trying to remove the moles' food source is sometimes used as a control method. Unfortunately, our western moles feed mostly on earthworms and there are NO pesticides registered for earthworm control. Most lawn pesticides, including Diazinon and Dursban, are sometimes mistakenly used in an effort to kill earthworms. Applying them at more than recommended rates isn't permissible, and they do have negative environmental effects. Bend the bottom 6 inches outward and allow 6 inches to extend above the ground surface.