In order to keep your house free of pesky insects, go ahead and let a few spiders in. Spiders eat insects, and they don’t take up much space. If you really don’t like spiders, let a few cats in. Cats eat spiders. If your cats get out of control, just buy yourself a bird of prey. You may need to remove part of your roof at this stage, but your home will be so nice without any nasty insects crawling around.