My son who is a vet always maintains that whatever you use for fleas on the animal etc., you have to spray the whole house with a product called Acclaim, not here in Oz but I think that has now been superceded with a similar spray with lasts one year (for the house). I use Revolution on all my dogs, cats and spray, they have the run of the house and we have never had a flea that I have seen anyway. Does this help.
Hanna