Informing Tenant Unsanitary Apartment Condition Is “Nuisance”

Q A tenant on the ground floor of my building keeps complaining about mice. I have had an exterminator visit every month, and he will continue to visit. However, she is the only tenant who complains of rodents, and the exterminator has told me, and her, that she has rodents because she does not keep her apartment clean. I am afraid her unsanitary apartment is going to keep attracting rodents as the winter approaches and possibly bring them into the rest of the building.