They are inexpensive and easy to use. However, they do not prevent egg development. They need to be used weekly. We recommend sprays that contain IGR's and effective adult, flea killing insecticides. Our favorite is a product by Vetkem called Siphotrol Area Treatment.
Sprays are safer than foggers, but they require more labor to be truly effective.
Using a spray, you can treat individual rooms. The re-entry period, the time which you and your pet must stay out of the room, is usually just an hour. Foggers, on the other hand, have a re-entry period of 6 to 8 hours. The vibration of the vacuum stimulates pre-adult fleas to come out of their cocoon. Replace furniture to original locations and spray the middle of the room.