I repeatedly see the assertion that lots of mole activity is an indicator of
grub infestation. We have a lot of Townsends moles and I haven't found a
corresponding abundance of grubs in our soil, but earthworms are aplenty.

This is an interesting factsheet I pulled up - about Townsends in BC - that
covers their behavior and diet in detail. Really very interesting. Thought
others might enjoy reading it. Also note it says earthworms comprise over
70% of their diet, which certainly confirms my experience.
http://wlapwww.gov.bc.ca/wld/documen...nsendsmole.pdf

Perhaps the earthworm/grub connection holds true for other species.