Yes, your house can be swarming with spiders. If your guests get the willies from these crawly, hairy arachnoids, then plaster all your windows with Black Widows. Mix it up too, that is, turn them upside down, flop them, and add two spiders to one window. You can create a house full of spiders very quickly with these Halloween decorative posters!. WOWindow Posters are backlit plastic window posters (34.5″x60″) that light up with inside lights for the surprise of passersby. Just hang them up in 30 seconds and leave your lights on. Our posters will do the rest! Our posters are the highest quality special effect available for thematic window decorating.