Two winters ago, we did nothing as I had in the past with no issues, that Spring we opened up to several large holes in screens and a few in the canvas. With mouse droppings and urine everywhere ...Last winter we did it all, thought we sealed all openings with foam spary, gaskets between roof and sidewalls, taped and screened furnace, fridge openings- Bounce sheets, entire box strewn throughout, Irish Spring soap throughout and outside as well..dog liked it...I also through in a couple of boxes of D-Con for good measure. This spring opened up to chewed curtains, cushions and bedcovers. Had to invest in new mattresses, wife too grossed out to sleep on them again, new curtains and again had to clean away stains with Instagone- great product by the way. In my opinion the only thing that worked was the D-Con, found the carcasses stuck to curtains this spring. Next Fall I will remove all mattresses, cushions, curtains etc and load up on D-Con, hopefully next Spring I won't still smell the mothballs....Good luck.