Cut six lemons into quarter pieces.
Boil your lemons quarters in a large pot of containing 1 quart of water for 20 minutes.
Steep your lemon and water mixture by letting it sit overnight to make sure that all of the lemon oil comes out of the lemon's peel.
Put your lemon mixture into a spray bottle. After your lemons have boiled and then soaked overnight, your mixture is ready. Fill a clean spray bottle with your mixture.
Spray your furniture with the lemon mixture. Apply your lemon spray liberally on all of your furniture and any other surfaces that are infested with fleas.