Bugs in TT when not in use?

Our invasion was lady bugs. Everywhere you turned...more. They seemed to love the large rear window where it was warm and you could see through the day shades to all these little critters. We'd gather up a handful and toss them out the door. Went on for weeks and I THINK we've finally got it under control....haven't seen any for about 6 weeks. Hadn't thought about asking our bug guy how much extra to spray the trailer....he's a long-time friend and I'd bet the answer is $0. I can afford that! For winter, we've always done the fabric softener sheet thing....according to some it works great, according to others it's a waste of time. In any event, we've never had mice or other critters and the trailer does smell wonderful. For a couple of dollars, we'll do it again for whatever reason.