Borax is one of the best things in the world for a flea infestation.
You sprinkle in under the couch cushions, between mattresses and protectors (or sheets, but that isnt advisable), under rugs, etc.
It destroys fleas, flea eggs, flea larvae, and nearly anything else. It is highly toxic and has no antidote since its not a poison-a small amount will easily kill a child or animal.
Its one of the many things that 99.9% of the population has no business using.
We also use it to get the meat off of turkey wings. You just pour borax all over them and leave them outside for a day or two-all the meat is gone and bone is clean. It should be a last resort, but an exterminator would be better.
A protected dog and an exterminator is a much better route. Just be sure to vacuum after the spraying and either dispose of the bag or if bagless cut up a flea collar in the container and clean thoroughly.
Family in pest control, and Im NA-we use it extensively for other things.