Sodium tetraborate, commonly known as borax, is a naturally occurring mineral compound consisting of sodium, boron, oxygen and water. Borax has many household uses, including cleaning laundry, removing stains from metal and softening hard water. While killing fleas is not one of the listed uses for 20 Mule Team Borax, sodium tetraborate is indeed toxic to fleas and other insects. You can rid your home of these pests by sprinkling borax of any brand around the home wherever fleas are found.
Crumple a piece of newspaper and stuff it inside the lid of the jar to help the lid keep its shape. Place the lid on the ground and punch approximately a dozen holes through the lid with the hammer and nail.
Fill the jar with borax and attach the lid. Sprinkle the borax, by turning the jar upside-down, anywhere in your home you've seen fleas. Be sure to thoroughly dust any carpeted areas and upholstered furniture as well as any cracks and crevices where fleas can hide. Sprinkle borax around the exterior sides of the house, including porch areas, creating a perimeter barrier against fleas.
Vacuum all areas treated with borax. Dispose of the vacuum bags by tightly sealing the vacuum bag inside of a plastic trash bag.
Sprinkle and wash any clothes, bedding, towels and stuffed animals with borax that may have been exposed to fleas. Repeat the treatments as needed.
Borax is poisonous to mammals if ingested, so it should be used cautiously around children and pets.