The vast majority are in the egg and larval stages of development. Unfortunately, most owners first want to spray their yard. A lovely way to spend an afternoon I am sure, but not the most effective way to control fleas. Creepy, I know. Remember that the flea eggs drop off of ol' Blue, right into that groovy orange and yellow shag carpet you have had since 1977.
Carpet provides the ideal microenvironment for flea development to take place.
This idea is championed by a professor of parasitology at my alma mater, Kansas State University. He believes that an integrated approach to flea control, attacking all stages of the life cycle on the animal and in its environment produces the best results. Let's get specific. Environmental treatment for fleas begins with thorough vacuuming of the entire indoor area, including upholstery. IGR's are chemicals such as methoprene and pyripoxifen that prevent the development of flea eggs and larva.