About 20 years ago I moved into a house that had LOTS of cockroaches. I bought a $7 can of 'Pruff' at the hardware store. It is boric acid and it said safe for plants, animals and kids. It is a blue powder that you put a teaspoon inside drawers, cracks in wood, anyplace a creepy critter would crawl through or hide. It takes up to three months to work because new eggs are hatching, but after that I had NEVER seen another cockroach in that house and I lived there another 5 years. I didn't have ferrets then, so you will need to reed the ingredients. It has been a long time and they could have change it. If in doubt, run the list of ingredients past your vet. [Posted in FML issue 4684]