In the last few months ive watched and exterminated huge armys of spiders coming into my house. Typicaly i go in a room and find 20 or more small dots on the ceiling. Leaving them there is not an option because they grow big. So i get the vacuum cleaner, some tissue paper and a spray foam cleaner and clear them up. Within 3 to 4 hours theres more. This has been happening on an almost daily basis