Okay..well..this comes from experience...unfortunately! My husband's old apartment had RATS!! Yup....big, wet rats. They came from the sewer/toilet!! I know I know....freaking GROSS!! I think......I might be wrong here.......but you can tell RATS from MICE b/c rats are bigger and have long tails...mice are usually small and have short tails... Ohhhh...that has brought back soo many sick memories! If possible, I would call on the men in the white suits to spray!