Slugs can't stand cinnamon, so look for signs of their preferred pathways into your home and intercept with plenty of cinnamon powder or oil to send them on their way.
Ants hate the smell of cinnamon and inhaling it can cause them suffocation, so find their entry points and sprinkle a thick borderline of cinnamon powder to keep them out.
Signs of a cockroach infestation include droppings, eggs, shed skins, or bad smells. Target potential entrances into your kitchen with cinnamon to repel them.
You can keep wasps far from your yard with the help of cinnamon. Just sprinkle, spray, or keep bowls of cinnamon around your garden table where there might be food and drink.