A vast majority of our house is 'all natural' and local and hand made, but we do want an efficient and bug proof home, so we do use some store bought products. This Great Stuff product is pretty cool. It's the expanding foam that ends up looking like, and acting like, insulation. We built our roof out of green lumber, and as it's shrinking as it dries, cracks between pieces are showing up.
By putting this foam into the cracks, not only are we making the ceiling more airtight, but making it a lot harder for the ants and termites to get in. In the photo, you can see the white goop in the cracks. It actually ages to a nice yellow, very similar to that blonde wood color.