So there is a type of spray used on boats to get rid of spiders. As you can imagine, having an in closed space near the water is prime real estate for spiders. The spray works by making it impossible for spiders to make webs around it. You just use it on all your window frames. Spiders won’t pass those lines because they sense that they can"t make webs there. I use the one from Yachticon, don’t know if you can order it everywhere, but it works wonders.