Diatomaceous Earth—always make sure to get food grade. There’s another kind (for swimming pool filters, I think) that’s toxic to ingest.
Also good for pets. I use it to worm my cats when needed. Just a good pinch (1/8 to 1/4 teaspoon) in a serving of canned cat food once a day for a few days usually does the trick.
Everyone in our household, human and feline, gets a dose of food-grade diatomaceous earth every day. We humans drink it with our morning juice - a bit gritty, but not too bad. We give it to the cats every with meal because there’s an ongoing Florida flea problem we’ve been unable to overcome, and we don’t want them to get tapeworms.
Heh. I got some a few years ago for the army of crickets that were coming onto my property from the vacant rent-house next door. Who would’ve guessed it was good for so many other things as well? :-)
Food grade DE is also great for dusting poultry. Kills mites and lice through dessication. Completely nontoxic. But be careful not to breathe it in.