Diatomaceous Earth

Yes, diatomaceous earth is a real thing for ticks, and yes, it kills them. The honest answer about where it actually works is more complicated than most sites let on.

DE is fossilized algae ground into a fine powder. Under a microscope it's sharp. When ticks walk through it, it damages their waxy outer coating and they dehydrate and die. It's a mechanical kill, not chemical, so there's no resistance issue and food-grade DE is non-toxic to people, pets, and most beneficial insects.

The limitation is water. The moment DE gets wet, it stops working until it dries again. In a yard during tick season, keeping open ground dry enough for DE to work consistently is essentially impossible. Rain, morning dew, irrigation, and humidity all neutralize it.

Where DE Actually Works

Dry, sheltered spots. Along the base of the house foundation, under covered porches, around wood piles with overhead cover, inside dry sheds, along fence lines in full sun with good drainage, in the gaps of stacked stone walls. These happen to be places where ticks concentrate, so DE in those spots is genuinely useful.