Thanks, Tekkie. The cats do a perfect job of keeping the living spaces clear. Between floors is trickier. A $3 box of d-Con from Lowe's does seemed to have fixed the problem. I used the d-Con that has the poison set inside a plastic box with an entry just big enough for a mouse. I removed a downstairs ceiling smoke detector and its "original built" electrical box to access the crawlspace between upstairs and downstairs. I set the d-Con inside the crawlspace on Sunday. Today (Tuesday) I installed a new "after-built" electrical box and checked the d-Con. A big chunk was missing. Feline #1 has not been stalking lately. (Feline #2 prefers gets his kicks stalking Feline #1.) I have not noticed any strange odors yet but expect to. Or maybe the deceased will dry up in the heat, and I may be spared the odor.