As far as how well this works, I have yet to see. However, application is quite messy. The fine powder gets into the air very quickly and you should wear a face mask to help keep it out of your lungs. Also you should use it in a well ventilated area to help dispurse the powder in the air. It is also hard to get deep into the carpet. When I vacuumed the visible powder (as per the instructions), I got more powder up than I expected. Wash your clothes as soon as possible afterwards to get the powder out of them.
This is THE product that helped eradicate fleas in our cats. Topical treatments (Frontline) gave relief but adding Fleabusters to the mix ended the invasions. I've even put it on small carpet squares in otherwise uncarpeted spaces and that seems to help stop reinfestation.