diatomaceous earth. It’s actually the fossilized remains of microscopic shells. When these remains come into contact with insects, it pierces their shells, so the pests die by dehydration. However, when people touch DE, it’s as soft to the touch as talcum powder and it’s nontoxic. If you have ants or roaches, sprinkle DE around the foundation of your home but not where ladybugs or other beneficial bugs live. Putting it directly on ant piles is also effective. Then, sprinkle it in areas where ants and roaches are most likely to enter your home.
Make sure you buy food grade DE. The other kind of diatomaceous earth is widely used in swimming pools and it is toxic.
even though it’s safe for people and pets, the dust can irritate lungs, especially with prolonged exposure, so wear a mask if you have a big project.