Borax. Spread it into all the corners, esp. around doors, and if you have carpet, sweep it into the carpet. The crystals will cut into the exoskeletons and kill them.
You could also try Demon WP which is an incredibly potent insecticide, but I wouldn’t recommend spraying your carpets if you have toddlers or other pets.
In before the first “You could burn it down” post...
You will have to bomb it with insect bomb several times without you and yours in that house. You will also have to get the fleas off of the source, dogs or cats?
They have some great products at the vets in a can that you can use after the bombing.
You have to kill the eggs or you will still get fleas.
Ugh. I’d get rid of the fleas and keep the cat.
Poor kitty.
Also, why are you getting rid of the cat? A flea dip, some flea medication, and a flea collar worn for about 6 weeks will ensure that kitty is free of them.
Diatomaceous earth (Shell flour) is another non toxic bug controller that works the same as Borax.
We began Advantage treatment (Google Advantage and Fleas), took them out of the house to a local park (used carriers), but before we left we prepped the house and bombed it with pesticide. Follow the directions thoroughly. We stayed out of the house for the recommended time and came back later. We continued the Advantage treatment and the fleas were permanently eliminated. Also, the cats were strictly indoor after that because they can pick up too many pests and diseases outside.
Borax as the other poster said or DE powder. It’s ground up sea shells so no chemicals.
Removing the cat will have them jumping on and biting you, be prepared for that.
Some will suggest diatomaceous earth but it’s fine and does become airborne, so using it in carpets and such, spread around on the floors of an occupied dwelling, can create problems. It will eventually kill insects including fleas by desiccation but there are issues with dust, breathing and intake filters for climate control.
Vacate the house for a few days and have a pest service fog/gas the interior. Vacuum very frequently after you return. You may need to repeat the treatment. Over time you’ll have them gone but a heavy infestation takes effort to completely remove.
If the cat spent much time outdoors there may be a problem there, too.
DE.....DE
Keep the cat indoors and treat with Advantage a couple of months. Poor kitty. And as other posters have said- Borax in a salt shaker all over the house. I once bombed twice in a heavily infested rental amd Borax is what did the trick. And we kept our cats who were under siege.
Go to a vet and buy something called “Fleabusters”
It’s something like 60% ortho-yada-boric acid.
Years back I had an infestation and about two tablespoons spread on the carpet wiped em!
why would you get rid of your cat?????? that’s ridiculous. use diatomaceous earth in the house and on the cat and the fleas will disappear.
About 5 or 6 years ago, our cats brought in a massive flea infestation. We tried for 2 months to get rid of the fleas, but it was almost impossible. Then we discovered flea traps.
A rectangular plastic plate about 10”x8” with an elevated cover wwith a small light bulb. The lower part has a sticky sheet of glue impregnated with flea pheromones. Put the trap in a room and turn on the trap’s small light (heat source). In an hour check the trap and there will be 50 or 60 of the biting pests stuck to it. A few days later and you’ll wonder where all the fleas came from and how they managed to find a place on the glue pad to stick themselves. The traps usually cost about $15 and replacement sheets of pheromone stick stuff are a couple bucks.
###
Put the cat outside on a leash....and open the door.
Lots of good advice so far - it isn’t the cat’s fault - multiple treatments even after it looks like the fleas are gone. Then be vigilant and inspect the cat often.
rubbing alcohol in 1$ squirt bottles. keep it with you at all times and shoot the little buggers when ever you see them. the cloud of alcohol vapor envelops them and makes them drunk and shrivel and die.