Orange Guard is an orange oil based insecticide designed to be used as a direct spray on insects. It does not leave any residual and therefore will not work for extended control on fleas. In order to kill fleas and knockout the population, you have to kill all life stages. This requires the use of an Insect Growth Regulator as well as an insecticide that will last long enough to kill the adults once they emerge from the pupal casings.
Remember, when you see adult fleas, you are only seeing around 5% of the overall population. Its the other 95% you need to be concerned about. Products such as Precor 2625
, etc will do a much better job of controlling fleas long term.