If all they eat is bugs and worms what can they hurt in the yard?
...they dig tunnels all over your yard, during the process they kill your grass.....the tunnels can sink in making your yard lumpy ....if they aren't controlled, they can tunnel near/under the foundation of your home causing weak spots/water damage in extreme circumstances
...many years ago, we looked at a home for sale and I could barely stand up in the back yard, like I was drunk.....kept walking over these Mole tunnels and the earth would give away....a section of the brick wall on the back of the home was pulling away due to the weakened foundation from extensive Mole tunnels
...many times treating your yard for Grubs will get rid of the Moles, Moles like to eat Grubs and when their food supply is gone, they soon leave too....usually if you watch closely, you can see them working under the surface of your yard because the turf moves up and down from their diging activity....a well aimed shovel head will stop the digging activities of that particular Mole, permanently