Flea eggs hatch every 3 days, so by sprinkling your floors for at least 9 days, vacuuming each 3rd day for 9 days, takes you through the complete life cycle of flea life. Be sure and empty your vacuum after each cleaning or the pests will just crawl back out and re-infest your home! You can also salt porches, doghouses and kennels to kill eggs & maintain flea control. Borax works as an alternative to salt but has a few cautions. In high humidity areas you may need to use a dehumidifier with the salt treatment for its use to be effective.