And for those of us who have septic systems (vs. sewers), moles can
devastate the drain field and cause it damage. It can lead to premature
failure or blockages in some cases. Most of the time it is benign, but if
the moles get too frisky, I have used a homemade castor oil spray to make
the earthworms less enticing. It works in a small area like my drain field.

Martha Jordan
Everett, WA